Academic literature on the topic 'Immersed boundary method (IBM)'
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Journal articles on the topic "Immersed boundary method (IBM)"
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Wu, Y. L., C. Shu, and H. Ding. "Simulation of Incompressible Viscous Flows by Local DFD-Immersed Boundary Method." Advances in Applied Mathematics and Mechanics 4, no. 03 (2012): 311–24. http://dx.doi.org/10.4208/aamm.10-m1171.
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AbstractA local domain-free discretization-immersed boundary method (DFD-IBM) is presented in this paper to solve incompressible Navier-Stokes equations in the primitive variable form. Like the conventional immersed boundary method (IBM), the local DFD-IBM solves the governing equations in the whole domain including exterior and interior of the immersed object. The effect of immersed boundary to the surrounding fluids is through the evaluation of velocity at interior and exterior dependent points. To be specific, the velocity at interior dependent points is computed by approximate forms of solution and the velocity at exterior dependent points is set to the wall velocity. As compared to the conventional IBM, the present approach accurately implements the non-slip boundary condition. As a result, there is no flow penetration, which is often appeared in the conventional IBM results. The present approach is validated by its application to simulate incompressible viscous flows around a circular cylinder. The obtained numerical results agree very well with the data in the literature.
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Zhao, Xiang, Liming Yang, Chang Xu, and Chang Shu. "An overset boundary condition-enforced immersed boundary method for incompressible flows with large moving boundary domains." Physics of Fluids 34, no. 10 (2022): 103613. http://dx.doi.org/10.1063/5.0122257.
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Conventional immersed boundary methods (IBMs) have greatly simplified the boundary condition treatment by interpreting boundaries as forces in the source terms of governing equations. In conventional IBMs, uniform meshes of very high resolution must be applied near the immersed boundary to treat the solid–fluid interface. However, this can induce a high computational cost for simulating flows with large moving boundary domains, where everywhere along the trajectory of the moving object must be refined isotropically. In the worst scenario, a global refinement is required when the object is moving arbitrarily in the entire computational domain. In this work, an overset boundary condition-enforced immersed boundary method (overset BC-enforced IBM) is proposed to simulate incompressible flows with large moving boundary domains efficiently. In the proposed overset BC-enforced IBM, a locally refined uniform mesh is applied and fixed on the moving object to account for the local motions, e.g., the rotation and deformation of the object, while the global motion of the object is handled by embedding the locally refined mesh in a coarser background mesh. Both the local mesh and the global background mesh can be generated automatically using the Cartesian approach to avoid the cumbersome boundary treatment. Since the mesh refinement is local, considerable computational savings can be achieved. The overset BC-enforced IBM is combined with the lattice Boltzmann flux solver to simulate various fluid–structure interaction problems with rigid and deformable boundaries.
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Hu, Yang, Decai Li, Shi Shu, and Xiaodong Niu. "An Efficient Immersed Boundary-Lattice Boltzmann Method for the Simulation of Thermal Flow Problems." Communications in Computational Physics 20, no. 5 (2016): 1210–57. http://dx.doi.org/10.4208/cicp.090815.170316a.
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AbstractIn this paper, a diffuse-interface immersed boundary method (IBM) is proposed to treat three different thermal boundary conditions (Dirichlet, Neumann, Robin) in thermal flow problems. The novel IBM is implemented combining with the lattice Boltzmann method (LBM). The present algorithm enforces the three types of thermal boundary conditions at the boundary points. Concretely speaking, the IBM for the Dirichlet boundary condition is implemented using an iterative method, and its main feature is to accurately satisfy the given temperature on the boundary. The Neumann and Robin boundary conditions are implemented in IBM by distributing the jump of the heat flux on the boundary to surrounding Eulerian points, and the jump is obtained by applying the jump interface conditions in the normal and tangential directions. A simple analysis of the computational accuracy of IBM is developed. The analysis indicates that the Taylor-Green vortices problem which was used in many previous studies is not an appropriate accuracy test example. The capacity of the present thermal immersed boundary method is validated using four numerical experiments: (1) Natural convection in a cavity with a circular cylinder in the center; (2) Flows over a heated cylinder; (3) Natural convection in a concentric horizontal cylindrical annulus; (4) Sedimentation of a single isothermal cold particle in a vertical channel. The numerical results show good agreements with the data in the previous literatures.
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LI, Q., C. SHU, and H. Q. CHEN. "SIMULATION OF INCOMPRESSIBLE VISCOUS FLOWS BY BOUNDARY CONDITION-IMPLEMENTED IMMERSED BOUNDARY METHOD." Modern Physics Letters B 23, no. 03 (2009): 345–48. http://dx.doi.org/10.1142/s0217984909018369.
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A new numerical approach is presented in this work to simulate incompressible flows. The present approach combines the ideas of the conventional immersed boundary method (IBM) for decoupling the solution of governing equations with the solid boundary and the local domain-free discretization (DFD) method for implementation of boundary conditions. Numerical results for simulation of flows around a circular cylinder showed that the present approach can provide accurate solutions effectively.
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JIANG, XIAOHAI, ZHIHUA CHEN, and HONGZHI LI. "NUMERICAL INVESTIGATION ON THE INTERACTION OF CYLINDER AND SHOCKWAVE BASED ON THE IMMERSED BOUNDARY METHOD." Modern Physics Letters B 23, no. 03 (2009): 317–20. http://dx.doi.org/10.1142/s0217984909018291.
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The immersed boundary method (IBM) is an innovative approach for modeling flow with complex geometries and is more efficient than traditional method. In the present investigation, the shock wave propagation over one circular cylinder is simulated numerically with the Ghost-Body Immersed Boundary Method and high-resolution Roe scheme. To validate the IBM, a plane incident shock wave passing through a square cylinder is predicted and good agreement with previous experiments was obtained. Then based on our calculation, the reflection and diffraction processes of a shock wave passing through a circular cylinder were visualized and discussed in detail.
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Wu, Jiayang, Yongguang Cheng, Chunze Zhang, and Wei Diao. "Three-Dimensional Simulation of Balloon Dynamics by the Immersed Boundary Method Coupled to the Multiple-Relaxation-Time Lattice Boltzmann Method." Communications in Computational Physics 17, no. 5 (2015): 1271–300. http://dx.doi.org/10.4208/cicp.2014.m385.
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AbstractThe immersed boundary method (IBM) has been popular in simulating fluid structure interaction (FSI) problems involving flexible structures, and the recent introduction of the lattice Boltzmann method (LBM) into the IBM makes the method more versatile. In order to test the coupling characteristics of the IBM with the multiple-relaxation-time LBM (MRT-LBM), the three-dimensional (3D) balloon dynamics, including inflation, release and breach processes, are simulated. In this paper, some key issues in the coupling scheme, including the discretization of 3D boundary surfaces, the calculation of boundary force density, and the introduction of external force into the LBM, are described. The good volume conservation and pressure retention properties are verified by two 3D cases. Finally, the three FSI processes of a 3D balloon dynamics are simulated. The large boundary deformation and oscillation, obvious elastic wave propagation, sudden stress release at free edge, and recoil phenomena are all observed. It is evident that the coupling scheme of the IBM and MRT-LBM can handle complicated 3D FSI problems involving large deformation and large pressure gradients with very good accuracy and stability.
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Chen, Yong Guang, and Li Wan. "Immersed Boundary Lattice Boltzmann Method to Simulate Fluid Flows with Flexible Boundaries." Applied Mechanics and Materials 670-671 (October 2014): 659–63. http://dx.doi.org/10.4028/www.scientific.net/amm.670-671.659.
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The immersed boundary method (IBM) for the simulation of the interaction between fluid and flexible boundaries in combination with the lattice Boltzmann method (LBM) is described. The LBM is used to compute the flow field, the interaction between fluid and flexible boundaries to be treated by the IBM. To analyze the key factors of combination method and implementation process. An example is presented to verify the efficiency and accuracy of the described algorithm. These will provide a base for large scale simulation involving flexible boundaries in the future.
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Bao, Jingyi, Fotini Katopodes Chow, and Katherine A. Lundquist. "Large-Eddy Simulation over Complex Terrain Using an Improved Immersed Boundary Method in the Weather Research and Forecasting Model." Monthly Weather Review 146, no. 9 (2018): 2781–97. http://dx.doi.org/10.1175/mwr-d-18-0067.1.
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Abstract The Weather Research and Forecasting (WRF) Model is increasingly being used for higher-resolution atmospheric simulations over complex terrain. With increased resolution, resolved terrain slopes become steeper, and the native terrain-following coordinates used in WRF result in numerical errors and instability. The immersed boundary method (IBM) uses a nonconformal grid with the terrain surface represented through interpolated forcing terms. Lundquist et al.’s WRF-IBM implementation eliminates the limitations of WRF’s terrain-following coordinate and was previously validated with a no-slip boundary condition for urban simulations and idealized terrain. This paper describes the implementation of a log-law boundary condition into WRF-IBM to extend its applicability to general atmospheric complex terrain simulations. The implementation of the improved WRF-IBM boundary condition is validated for neutral flow over flat terrain and the complex terrain cases of Askervein Hill, Scotland, and Bolund Hill, Denmark. First, comparisons are made to similarity theory and standard WRF results for the flat terrain case. Then, simulations of flow over the moderately sloped Askervein Hill are used to demonstrate agreement between the IBM and terrain-following WRF results, as well as agreement with observations. Finally, Bolund Hill simulations show that WRF-IBM can handle steep topography (standard WRF fails) and compares well to observations. Overall, the new WRF-IBM boundary condition shows improved performance, though the leeside representation of the flow can be potentially further improved.
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SALEEL, C. A., A. SHAIJA, and S. JAYARAJ. "COMPUTATIONAL SIMULATION OF FLUID FLOW OVER A TRIANGULAR STEP USING IMMERSED BOUNDARY METHOD." International Journal of Computational Methods 10, no. 04 (2013): 1350016. http://dx.doi.org/10.1142/s0219876213500163.
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Handling of complex geometries with fluid–solid interaction has been one of the exigent issues in computational fluid dynamics (CFD) because most engineering problems have complex geometries with fluid–solid interaction for the purpose. Two different approaches have been developed for the same hitherto: (i) The unstructured grid method and (ii) the immersed boundary method (IBM). This paper details the IBM for the numerical investigation of two-dimensional laminar flow over a backward facing step and various geometrically configured triangular steps in hydro-dynamically developing regions (entrance region) as well in the hydro-dynamically developed regions through a channel at different Reynolds numbers. The present numerical method is rooted in a finite volume approach on a staggered grid in concert with a fractional step method. Geometrical obstructions are treated as an immersed boundary (IB), both momentum forcing and mass source terms are applied on the obstruction to satisfy the no-slip boundary condition and also to satisfy the continuity for the mesh containing the immersed boundary. Initially, numerically obtained velocity profiles and stream line plots for fluid flow over backward facing step is depicted to show its excellent agreement with the published results in various literatures. There after profiles and plots in the channel with triangular steps are also being unveiled with in depth elucidation. Results are presented for different Reynolds numbers.
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Ye, Haixuan, Yang Chen, and Kevin Maki. "A Discrete-Forcing Immersed Boundary Method for Moving Bodies in Air–Water Two-Phase Flows." Journal of Marine Science and Engineering 8, no. 10 (2020): 809. http://dx.doi.org/10.3390/jmse8100809.
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For numerical simulations of ship and offshore hydrodynamic problems, it is challenging to model the interaction between the free surface and moving complex geometries. This paper proposes a discrete-forcing immersed boundary method (IBM) to efficiently simulate moving solid boundaries in incompressible air–water two-phase flows. In the present work, the air–water two-phase flows are modeled using the Volume-of-Fluid (VoF) method. The present IBM is suitable for unstructured meshes. It can be used combined with body-fitted wall boundaries to model the relative motions between solid walls, which makes it flexible to use in practical applications. A field extension method is used to model the interaction between the air–water interface and the immersed boundaries. The accuracy of the method is demonstrated through validation cases, including the three-dimensional dam-break problem with an obstacle, the water exit of a circular cylinder, and a ship model advancing with a rotating semi-balanced rudder. The flow field, free-surface profile and force on the immersed boundaries (IBs) are in good agreement with experimental data and other numerical results.
Dissertations / Theses on the topic "Immersed boundary method (IBM)"
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Jadidi, Mansoor. "Numerical and Experimental Model of Healthy and Damaged Red Blood Cell Trajectories in Micro-channels." Thesis, Griffith University, 2023. http://hdl.handle.net/10072/421347.
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Motivation: Red blood cells (RBCs) are the most common cells in the blood due to their high concentration. The RBC has a deformable membrane enclosing a jelly-like fluid known as the cytosol. For many years, the dynamics of RBCs has attracted growing interest both numerically and experimentally in various fields of research on biological systems. Owing to their high deformability, RBCs exhibit complex dynamic behaviours in micro-vessels where Reynolds numbers (Re) are less than unity (Re < 1). First, a healthy RBC at a low shear rate or a high viscosity contrast (λ - defined as the ratio of viscosities between RBC cytosol and external fluid), may tumble, i.e., the whole RBC rotates continuously in the original shape like a rigid body. Second, at a high shear rate or a low viscosity contrast (λ), the RBC may exhibit a tank-treading motion, i.e., its membrane rotates around the cytosol which maintains a fixed angle with respect to the flow direction. Finally, a healthy RBC migrates in the lateral direction towards the micro-vessel axis while moving in the longitudinal direction (downstream) of a micro-vessel.
Under physiological conditions, the RBC experiences a varying range of shear stresses (typically in the range of 1-10 Pa) in the circulatory system without exhibiting any physical signs of mechanical damage. Upon exposure to high shear stresses, such as those present within mechanical circulatory support, RBCs exhibit irreversible functional impairment called sub-haemolytic/sub-lethal damage. Sub-haemolytically damaged RBCs exhibit impaired mechanical properties that substantially alter bulk flow behaviour when compared with healthy RBCs. However, there has been little attention directed toward characterizing sub-haemolytic damage in literature. For better understanding, it is necessary to have a reliable model to predict the dynamics of sub-haemolytically damaged RBCs in micro-vessels in comparison with healthy RBCs.
Methods: Highly-efficient numerical approaches have been developed to investigate blood flow, with particular emphasis on the motion and deformation of RBCs under shear flow. Among these methods, the integration of the lattice Boltzmann method (LBM) and immersed boundary method (IBM) has received considerable attention. In this dissertation, a 2D in-house generated algorithm based on the LBM-IBM was utilised for the numerical simulations. Moreover, a spring-based model was applied to simulate the elastic behaviour of the RBC membrane. Finally, a microfluidic experimental system including flow control, image capture, and data acquisition was established to validate the numerical results with the experimental results.
Goal: The main focus of this dissertation was to establish a 2D LBM-IBM coupled with a spring-based model to simulate the trajectory of both healthy RBC and damaged RBC in Poiseuille flow in low Reynolds numbers (Re < 1), in which the numerical results are compared with the experimental ones to allow for model validation. The second aim of this study was to numerically simulate the tumbling and tank-treading-like motion of a single RBC (healthy and damaged) in a micro-channel. Finally, the third aim was to numerically simulate the effect of the viscosity contrast (λ) on the trajectory of an RBC in a micro-channel. λ is one of the important factors that can severely affect RBC dynamics and cell deformation in a shear flow. Because of computational complexity, little effort has been made to numerically model the effect of λ on RBC dynamics in flow in the literature, for this reason, most of the current simulation studies assume for simplicity the viscosity contrast of unity.
Results: Overall, the numerical results indicated a reasonable agreement with the observed experimental results. However, the numerical simulation predicts a larger migration (1.81 μm for the healthy RBC and 0.96 μm for the damaged RBC) compared to the experimental tests (1.20 μm for the healthy RBC and 0.41 μm for the damaged RBC). Moreover, the experimental results showed that at a certain distance from the entrance of the micro-channel, the RBCs have a rolling motion like a wheel but without lateral migration. Due to the deformability of the RBCs, this motion is unstable so that later on, the RBCs migrate laterally toward the centreline of the micro-channel. The results also showed that the distance at which rolling motion happens is greater for the damaged RBCs (~ 150 μm) compared to the healthy RBCs (~ 25 μm) because the damaged cells deform less. The numerical results confirm this result. It can be seen from the numerical results that the healthy RBC experiences the tank-treading motion compared to the damaged RBC that exhibits the tumbling motion. Furthermore, the numerical results indicated a significant impact on the RBC trajectory when λ = 5 compared to λ = 1. The higher viscosity contrast of 5 has less lift (5.06 μm) in comparison with the lower viscosity contrast of 1 (6.56 μm). In addition, for a fixed viscosity contrast λ of 10, as the rigidity of the RBC increases, its final lateral and longitudinal displacements decrease.<br>Thesis (PhD Doctorate)<br>Doctor of Philosophy (PhD)<br>School of Eng & Built Env<br>Science, Environment, Engineering and Technology<br>Full Text
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Noël, Emeline. "Simulation numérique directe d’écoulements à l’aide d’une méthode de frontière immergée." Thesis, Rouen, INSA, 2012. http://www.theses.fr/2012ISAM0020/document.
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Les travaux menés, depuis plusieurs années, au CORIA ont abouti à la construction d’un outil numérique (ARCHER) permettant la simulation numérique directe d’écoulements diphasiques et notamment l’atomisation d’un jet liquide à haute vitesse. Ce type de simulation permet de capturer les phénomènes d’atomisation au voisinage de l’injecteur difficilement caractérisables par les outils expérimentaux actuels. Ces simulations requièrent des conditions d’injection délicates à évaluer a priori car elles dépendent des caractéristiques de l’écoulement au sein de l’injecteur. Or, certains jets présentent une grande sensibilité à ces conditions d’injection. Dès lors, il est nécessaire de simuler l’écoulement au sein de l’injecteur afin d’appréhender la nature de cette sensibilité. L’utilisation d’un maillage cartésien par le code ARCHER conjuguée à la volonté de simuler le système d’atomisation dans son ensemble ont orienté ces travaux vers l’utilisation d’une méthode de frontière immergée. Ces travaux ont ainsi permis de reproduire des écoulements au sein d’injecteurs de forme quelconque tout en conservant le maillage cartésien d’origine, précieux tant pour l’efficacité du solveur que pour sa précision. Dans un premier temps, l’implantation dans le code ARCHER d’une méthode de frontière immergée a été réalisée et testée sur des configurations de canal et de conduite et de l’écoulement autour d’un cylindre. L’application de cette méthode a porté sur la simulation de l’écoulement au sein d’un injecteur triple disque mono-trou et a notamment permis de caractériser l’origine de l’écoulement secondaire formé dans l’orifice de décharge. Afin d’évoluer vers la construction d’un outil numérique capable de simuler le système d’atomisation dans son ensemble, un couplage entre la méthode de frontière immergée et la méthode Ghost fluid a été nécessaire. La version bi-dimensionnelle développée a été testée sur la relaxation d’une goutte posée sur une paroi. Cette version a permis de simuler des écoulements au sein de canaux à différents rapports de longueur sur diamètre et l’écoulement au sein d’une buse convergente. La simulation simultanée de l’écoulement interne et externe a permis de lier les fluctuations de vitesses des écoulements internes à la création de surface engendrée sur les écoulements externes<br>Since several years, the research conducted at the CORIA laboratory led to the development of a numerical tool (ARCHER) alllowing direct numerical simulations of two phase flows. In particular, the simulations of high speed liquid jet primary break-up have been strongly investigated. These simulations are able to capture primary break-up phenomena near the nozzle exit where experimental characterisations are difficult to conduct. These simulations need injection conditions tricky to gauge a priori, since they depend on the flow characteristics inside the nozzle. Moreover, some jets are highly sensitive to these injection conditions. Therefore, it becomes necessary to simulate the flow inside the nozzle to better understand this sensitive nature. The objective to simulate the whole atomization system guided the present work dedicated to the use of an immersed boundary method (IBM). Such an approach allows reproducing flows inside nozzles of arbitrary shape while keeping the original cartesian mesh valuable for numerical efficiency and accuracy. As a first step, the implementation of an IBM in ARCHER was carried out and tested on channels, pipes and uniform flows past a circular cylinder. An industrial application focused on the flow inside a triple disk compound injector. This work led to a refined description of the secondary flow origin in the discharge hole. In order to move towards the design of a numerical tool able to simulate the whole injection system, a coupling between IBM and the Ghost Fluid Method (GFM) has been found necessary. This allows accounting for two phase flows inside the nozzle where the dynamics of the triple line has to be considered. The bidimensional developments have been tested on drops released on walls. This version enabled to simulate flows inside channels with different ratios of length over diameter and the flow inside a convergent nozzle. The simultaneous computation of flows inside and outside nozzle has enabled to link the velocity fluctuations of internals flows to the surface setting-up gene-rated on external flows
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Mokhtarpour, Vanaki Shayan. "Numerical investigation of muco-ciliary transport." Thesis, Queensland University of Technology, 2020. https://eprints.qut.edu.au/203744/1/Shayan_Mokhtarpour%20Vanaki_Thesis.pdf.
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The human airways are protected from inhaled external substances by an extremely thin layer called airway surface liquid. This film of liquid captures most of the inhaled toxic particles and is constantly propelled back out of the airway by a dense mat of beating hair-like structures, thus cleansing the airways of inhaled pathogens. It is vital to better understand this clearance process under diseased conditions and to predict the fate of therapeutic drug particles after deposition. An advanced numerical model is developed to investigate these objectives, given that the complex nature of lung clearance limits the ability to conduct experiments.
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Sarkis, Bruno. "Étude numérique de la relaxation de capsules confinées par couplage des méthodes Volumes Finis - Éléments Finis via la méthode des frontières immergées IBM : influence de l'inertie et du degré de confinement." Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS184/document.
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Les capsules, formées d’une goutte protégée par une membrane élastique, sont très présentes naturellement et dans diverses applications industrielles, mais peu d’études ont exploré les phénomènes transitoires de leur relaxation. L’objectif est d’étudier l’influence de l’inertie et du confinement sur la relaxation d’une capsule sphérique (1) pré-déformée en ellipsoïde et relâchée dans un canal carré où le fluide est au repos, (2) sous écoulement dans un canal carré à expansion soudaine (‘marche’). La capsule est modélisée comme un fluide Newtonien dans une membrane hyper-élastique sans épaisseur ni viscosité, et simulée en couplant les méthodes Volumes Finis - Eléments Finis - frontières immergées. Sa relaxation dans un fluide au repos comporte 3 phases : amorçage du mouvement du fluide, phases rapide puis lente de rétraction de la membrane. Trois régimes existent selon le rapport de confinement et le rapport des nombres de Reynolds et capillaire : amortissements pur, critique ou oscillant. Un modèle de Kelvin-Voigt inertiel est proposé pour prédire les temps de réponse et aussi appliqué à une capsule en écoulement dans le canal microfluidique avec marche. La comparaison aux simulations 3D montre sa pertinence aux temps courts de la relaxation. Ces travaux ouvrent la voie à l’étude d’écoulements transitoires de capsules confinées dans des systèmes microfluidiques complexes<br>Capsules, made of a drop protected by an elastic membrane, are widly present in nature and in diverse industrial applications, but few studies have explored the transient phenomena governing their relaxation. The objective of the PhD is to study the influence of inertia and confinement on the relaxation of a spherical capsule (1) pre-deformed into an ellipsoid and released in a square channel where the fluid is quiescent, (2) flowing in a square channel with a sudden expansion (‘step’). The capsule is modeled as a Newtonian fluid in a hyperelastic membrane without thickness or viscosity and is simulated coupling the Finite Volume - Finite Element - Immersed Boundary Methods. Its relaxation in a quiescent fluid exhibits three phases: the initiation of the fluid motion, the rapid and then slow retraction phases of the membrane. Three regimes exist depending on the confinement ratio and the Reynolds to capillary number ratio: pure, critical or oscillating damping. A Kelvin-Voigt inertial model is proposed to predict the response time constants and also applied to a capsule flowing in the microfluidic channel with a step. The comparison to 3D simulations shows its relevance at short relaxation times. This work paves the way to the study of transient flows of capsules confined in microfluidic devices
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Fry, Benjamin. "Modélisation multi-échelle d'un lit granulaire entraîné par un écoulement cisaillé." Thesis, Toulouse, INPT, 2019. http://www.theses.fr/2019INPT0132.
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Dans cette thèse, on étudie le transport granulaire par charriage en régime établi d’un lit de grains soumis à un écoulement de Couette laminaire pour un rapport de densité fluide-grain de 2.5 et une gamme de nombre de Reynolds particulaire, Re p [0.1, 10], et de nombre de Shields, [0.1,0.7]. Toutes les échelles de cet écoulement diphasique (à l’exception des effets de lubrification) sont décrites via la résolution numérique des équations de Navier-Stokes en prenant en compte la présence des particules par une méthode de frontières immergées (IBM) couplée à un solveur granulaire (méthode des éléments discrets - DEM) qui résout les équations de Newton pour chaque particule ainsi que les contacts et frottements entre grains (résolution à l’échelle microscopique). Un changement d’échelle est ensuite effectué afin d’obtenir une description de l’écoulement via des champs continus équivalents (description à l’échelle mésoscopique). Les simulations IBM-DEM permettent de quantifier chacun des termes du modèle dit mésoscopique et de caractériser la rhéologie de chaque phase ainsi que du mélange. On effectue finalement un second changement d’échelle afin de réduire l’écoulement de grains observé à une singularité, qui correspond à une condition limite du point de vue de l’écoulement du fluide. Cette condition est du type de Navier. Les simulations IBM-DEM montrent que la longueur dite de glissement "équivalente" est directement proportionnelle au nombre de Shields<br>In this work, we consider the steady transport of a granular medium by a laminar Couette flow for a fixed density ratio of 2.5 and a range of particle Reynolds number, Re p [0.1, 10], and Shields number [0.1, 0.7]. All scales of this two-phase flow are captured (except for the lubrication effects). By solving the Navier-Stokes equations, taking into account the presence of particles using an Immersed Boundary Method (IBM) coupled to a granular solver (Discrete Elements Method - DEM) which solves the Newton equations for each particle, in particular grain-grain interactions (resolution at the microscopic scale). Up-scaling is then performed to describe the flow via equivalent continuous quantities (description at the mesoscopic scale). IBM-DEM simulations allow to quantify all the terms of the so-called mesoscopic model and to characterize the rheology of each phase and that of the equivalent mixture. A second up-scaling is finally performed to reduce the granular flow to a singularity, which corresponds to a boundary condition from the fluid view point. The boundary condition is of Navier’s type. The IBM-DEM simulations suggest that the corresponding "equivalent" slip-lenght scales as
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Madani, Kermani Seyed Hossein. "Application of immersed boundary method to flexible riser problem." Thesis, Brunel University, 2014. http://bura.brunel.ac.uk/handle/2438/9605.
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In the recent decades the Fluid-Structure Interaction (FSI) problem has been of great interest to many researchers and a variety of methods have been proposed for its numerical simulation. As FSI simulation is a multi-discipline and a multi-physics problem, its full simulation consists of many details and sub-procedures. On the other hand, reliable FSI simulations are required in various applications ranging from hemo-dynamics and structural engineering to aero-elasticity. In hemo-dynamics an incompressible fluid is coupled with a flexible structure with similar density (e.g. blood in arteries). In aero-elasticity a compressible fluid interacts with a stiff structure (e.g. aircraft wing) or an incompressible flow is coupled with a very light structure (e.g. Parachute or sail), whereas in some other engineering applications an incompressible flow interacts with a flexible structure with large displacement (e.g. oil risers in offshore industries). Therefore, various FSI models are employed to simulate a variety of different applications. An initial vital step to conduct an accurate FSI simulation is to perform a study of the physics of the problem which would be the main criterion on which the full FSI simulation procedure will then be based. In this thesis, interaction of an incompressible fluid flow at low Reynolds number with a flexible circular cylinder in two dimensions has been studied in detail using some of the latest published methods in the literature. The elements of procedures have been chosen in a way to allow further development to simulate the interaction of an incompressible fluid flow with a flexible oil riser with large displacement in three dimensions in future. To achieve this goal, a partitioned approach has been adopted to enable the use of existing structural codes together with an Immersed Boundary (IB) method which would allow the modelling of large displacements. A direct forcing approach, interpolation / reconstruction, type of IB is used to enforce the moving boundary condition and to create sharp interfaces with the possibility of modelling in three dimensions. This provides an advantage over the IB continuous forcing approach which creates a diffused boundary. And also is considered as a preferred method over the cut cell approach which is very complex in three dimensions with moving boundaries. Different reconstruction methods from the literature have been compared with the newly proposed method. The fluid governing equation is solved only in the fluid domain using a Cartesian grid and an Eulerian approach while the structural analysis was performed using Lagrangian methods. This method avoids the creation of secondary fluid domains inside the solid boundary which occurs in some of the IB methods. In the IB methods forces from the Eulerian flow field are transferred onto the Lagrangian marker points on the solid boundary and the displacement and velocities of the moving boundary are interpolated in the flow domain to enforce no-slip boundary conditions. Various coupling methods from the literature were selected and improved to allow modelling the interface and to transfer the data between fluid and structure. In addition, as an alternative method to simulate FSI for a single object in the fluid flow as suggested in the literature, the moving frame of reference method has been applied for the first time in this thesis to simulate Fluid-Structure interaction using an IB reconstruction approach. The flow around a cylinder in two dimensions was selected as a benchmark to validate the simulation results as there are many experimental and analytical results presented in the literature for this specific case.
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Falagkaris, Emmanouil. "Lattice Boltzmann method and immersed boundary method for the simulation of viscous fluid flows." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/33165.
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Most realistic fluid flow problems are characterised by high Reynolds numbers and complex boundaries. Over the last ten years, immersed boundary methods (IBM) that are able to cope with realistic geometries have been applied to Lattice- Boltzmann methods (LBM). These methods, however, have normally been applied to low Reynolds number problems. In the present work, an iterative direct forcing IBM has been successfully coupled with a multi-domain cascaded LBM in order to investigate viscous flows around rigid, moving and wilfully deformed boundaries at a wide range of Reynolds numbers. The iterative force-correction immersed boundary method of (Zhang et al., 2016) has been selected due to the improved accuracy of the computation, while the cascaded LB formulation is used due to its superior stability at high Reynolds numbers. The coupling is shown to improve both the stability and numerical accuracy of the solution. The resulting solver has been applied to viscous flow (up to a Reynolds number of 100000) passed a NACA-0012 airfoil at a 10 degree angle of attack. Good agreement with results obtained using a body-fitted Navier-Stokes solver has been obtained. At moving or deformable boundary applications, emphasis should be given on the influence of the internal mass on the computation of the aerodynamic forces, focusing on deforming boundary motions where the rigid body approximation is no longer valid. Both the rigid body and the internal Lagrangian points approximations are examined. The resulting solver has been applied to viscous flows around an in-line oscillating cylinder, a pitching foil, a plunging SD7003 airfoil and a plunging and flapping NACA-0014 airfoil. Good agreement with experimental results and other numerical schemes has been obtained. It is shown that the internal Lagrangian points approximation accurately captures the internal mass effects in linear and angular motions, as well as in deforming motions, at Reynolds numbers up to 4 • 104. Finally, an expanded higher-order immersed boundary method which addresses two major drawbacks of the conventional IBM will be presented. First, an expanded velocity profile scheme has been developed, in order to compensate for the discontinuities caused by the gradient of the velocity across the boundary. Second, a numerical method derived from the Navier-Stokes equations in order to correct the pressure distribution across the boundary has been examined. The resulting hybrid solver has been applied to viscous flows around stationary and oscillating cylinders and examined the hovering flight of elliptical wings at low Reynolds numbers. It is shown that the proposed scheme smoothly expands the velocity profile across the boundary and increases the accuracy of the immersed boundary method. In addition, the pressure correction algorithm correctly expands the pressure profile across the boundary leading to very accurate pressure coefficient values along the boundary surface. The proposed numerical schemes are shown to be very efficient in terms of computational cost. The majority of the presented results are obtained within a few hours of CPU time on a 2.8 GHz Intel Core i7 MacBook Pro computer with a 16GB memory.
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Rowlatt, Christopher Frederick. "Modelling flows of complex fluids using the immersed boundary method." Thesis, Cardiff University, 2014. http://orca.cf.ac.uk/63680/.
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This thesis is concerned with fluid-structure interaction problems using the immersed boundary method (IBM). Fluid-structure interaction problems can be classified into two categories: a remeshing approach and a fixed-grid approach. Both approaches consider the fluid and structure separately and then couple them together via suitable interface conditions. A common choice of remeshing approach is the Arbitrary-Eulerian-Lagrangian (ALE) technique. Whilst the ALE method is a good choice if deformations are small, it becomes computationally very expensive if deformations are large. In such a scenario, one turns to a fixed-grid approach. However, the issue with a fixed-grid approach is the enforcement of the interface conditions. An alternative to the remeshing and fixed-grid approach is the IBM. The IBM considers the immersed elastic structure to be part of the surrounding fluid by replacing the immersed structure with an Eulerian force density. Therefore, the interface conditions are enforced implicitly. This thesis applies the finite element immersed boundary method (IBM) to both Newtonian and Oldroyd-B viscoelastic fluids, where the fluid variables are approximated using the spectral element method (hence we name the method the spectral element immersed boundary method (SE-IBM)) and the immersed boundary variables are approximated using either the finite element method or the spectral element method. The IBM is known to suffer from area loss problems, e.g. when a static closed boundary is immersed in a fluid, the area contained inside the closed boundary decreases as the simulation progresses. The main source of error in such a scenario can be found in the spreading and interpolation phases. The aim of using a spectral element method is to improve the accuracy of the spreading and interpolation phases of the IBM. We illustrate that the SE-IBM can obtain better area conservation than the FE-IBM when a static closed boundary is considered. Also, the SE-IBM obtains higher order convergence of the velocity in the L2 and H1 norms, respectively. When the SE-IBM is applied to a viscoelastic fluid, any discontinuities which occur in either the velocity gradients or the pressure, introduce oscillations in the polymeric stress components. These oscillations are undesirable as they could potentially cause the numerics to break down. Finally, we consider a higher-order enriched method based on the extended finite element method (XFEM), which we call the eXtended Spectral Element Method (XSEM). When XSEM is applied to the SE-IBM with a viscoelastic fluid, the oscillations present in the polymeric stress components are greatly reduced.
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Cai, Shang-Gui. "Computational fluid-structure interaction with the moving immersed boundary method." Thesis, Compiègne, 2016. http://www.theses.fr/2016COMP2276/document.
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Dans cette thèse, une nouvelle méthode de frontières immergées a été développée pour la simulation d'interaction fluide-structure, appelée la méthode de frontières immergées mobiles (en langage anglo-saxon: MIBM). L'objectif principal de cette nouvelle méthode est de déplacer arbitrairement les solides à géométrie complexe dans un fluide visqueux incompressible, sans remailler le domaine fluide. Cette nouvelle méthode a l'avantage d'imposer la condition de non-glissement à l'interface d'une manière exacte via une force sans introduire des constantes artificielles modélisant la structure rigide. Cet avantage conduit également à la satisfaction de la condition CFL avec un pas de temps plus grand. Pour un calcul précis de la force induite par les frontières mobiles, un système linéaire a été introduit et résolu par la méthode de gradient conjugué. La méthode proposée peut être intégrée facilement dans des solveurs résolvant les équations de Navier-Stokes. Dans ce travail la MIBM a été mise en œuvre en couplage avec un solveur fluide utilisant une méthode de projection adaptée pour obtenir des solutions d'ordre deux en temps et en espace. Le champ de pression a été obtenu par l'équation de Poisson qui a été résolue à l'aide de la méthode du gradient conjugué préconditionné par la méthode multi-grille. La combinaison de ces deux méthodes a permis un gain de temps considérable par rapport aux méthodes classiques de la résolution des systèmes linéaires. De plus le code de calcul développé a été parallélisé sur l'unité graphique GPU équipée de la bibliothèque CUDA pour aboutir à des hautes performances de calcul. Enfin, comme application de nos travaux sur la MIBM, nous avons étudié le couplage "fort" d'interaction fluide-structure (IFS). Pour ce type de couplage, un schéma implicite partitionné a été adopté dans lequel les conditions à l'interface sont satisfaites via un schéma de type "point fixe". Pour réduire le temps de calcul inhérent à cette application, un nouveau schéma de couplage a été proposé pour éviter la résolution de l'équation de Poisson durant les itérations du "point fixe". Cette nouvelle façon de résoudre les problèmes IFS a montré des performances prometteuses pour des systèmes en IFS complexe<br>In this thesis a novel non-body conforming mesh formulation is developed, called the moving immersed boundary method (MIBM), for the numerical simulation of fluid-structure interaction (FSI). The primary goal is to enable solids of complex shape to move arbitrarily in an incompressible viscous fluid, without fitting the solid boundary motion with dynamic meshes. This novel method enforces the no-slip boundary condition exactly at the fluid-solid interface with a boundary force, without introducing any artificial constants to the rigid body formulation. As a result, large time step can be used in current method. To determine the boundary force more efficiently in case of moving boundaries, an additional moving force equation is derived and the resulting system is solved by the conjugate gradient method. The proposed method is highly portable and can be integrated into any fluid solver as a plug-in. In the present thesis, the MIBM is implemented in the fluid solver based on the projection method. In order to obtain results of high accuracy, the rotational incremental pressure correction projection method is adopted, which is free of numerical boundary layer and is second order accurate. To accelerate the calculation of the pressure Poisson equation, the multi-grid method is employed as a preconditioner together with the conjugate gradient method as a solver. The code is further parallelized on the graphics processing unit (GPU) with the CUDA library to enjoy high performance computing. At last, the proposed MIBM is applied to the study of two-way FSI problem. For stability and modularity reasons, a partitioned implicit scheme is selected for this strongly coupled problem. The interface matching of fluid and solid variables is realized through a fixed point iteration. To reduce the computational cost, a novel efficient coupling scheme is proposed by removing the time-consuming pressure Poisson equation from this fixed point interaction. The proposed method has shown a promising performance in modeling complex FSI system
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Lai, Xin. "Modeling and Numerical Simulations of Active and Passive Forces Using Immersed Boundary Method." Digital WPI, 2019. https://digitalcommons.wpi.edu/etd-theses/1334.
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This thesis uses the Immersed Boundary Method (IBM) to simulate the movement of a human heart. The IBM was developed by Charles Peskin in the 70’s to solve Fluid-Structure Interaction models (FSI). The heart is embedded inside a fluid (blood) which moves according to the Navier-Stokes equation. The Navier-Stokes equation is solved by the Spectral Method. Forces on the heart muscle can be divided into two kinds: Active Force and Passive Force. Passive includes the effect of curvature (Peskin’s model), spring model, and the torsional spring (or beam) model. Active force is modeled by the 3-element Hill model, which was used in the 30’s to model skeletal muscle. We performed simulations with different combinations of these four forces. Numerical simulations are performed using MATLAB. We downloaded Peskin’s code from the Internet and modified the Force.m file to include the above four forces. This thesis only considers heart muscle movement in the organ (macroscopic) scale.
Books on the topic "Immersed boundary method (IBM)"
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Roy, Somnath, Ashoke De, and Elias Balaras, eds. Immersed Boundary Method. Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-3940-4.
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Roy, Somnath, Ashoke De, and Elias Balaras. Immersed Boundary Method: Development and Applications. Springer Singapore Pte. Limited, 2021.
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Roy, Somnath, Ashoke De, and Elias Balaras. Immersed Boundary Method: Development and Applications. Springer, 2020.
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Yao, Guangfa. Immersed Boundary Method for CFD: Focusing on its Implementation. CreateSpace Independent Publishing Platform, 2018.
Find full textBook chapters on the topic "Immersed boundary method (IBM)"
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Luo, Haoxiang. "Immersed Boundary Method." In Encyclopedia of Microfluidics and Nanofluidics. Springer New York, 2015. http://dx.doi.org/10.1007/978-1-4614-5491-5_674.
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Luo, Haoxiang. "Immersed Boundary Method." In Encyclopedia of Microfluidics and Nanofluidics. Springer US, 2014. http://dx.doi.org/10.1007/978-3-642-27758-0_674-5.
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Ito, Kazufumi, and Zhilin Li. "Immersed Interface/Boundary Method." In Encyclopedia of Applied and Computational Mathematics. Springer Berlin Heidelberg, 2015. http://dx.doi.org/10.1007/978-3-540-70529-1_387.
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Krüger, Timm. "Fluid-structure interaction: the immersed boundary method." In Computer Simulation Study of Collective Phenomena in Dense Suspensions of Red Blood Cells under Shear. Vieweg+Teubner Verlag, 2012. http://dx.doi.org/10.1007/978-3-8348-2376-2_6.
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Gong, Z. X., H. X. Huang, and C. J. Lu. "Stability Analysis for the Immersed Boundary Method." In New Trends in Fluid Mechanics Research. Springer Berlin Heidelberg, 2007. http://dx.doi.org/10.1007/978-3-540-75995-9_241.
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Cai, Shang-Gui, Abdellatif Ouahsine, Julien Favier, and Yannick Hoarau. "Improved Implicit Immersed Boundary Method via Operator Splitting." In Computational Methods in Applied Sciences. Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-27996-1_3.
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Gounley, John, Erik W. Draeger, and Amanda Randles. "Immersed Boundary Method Halo Exchange in a Hemodynamics Application." In Lecture Notes in Computer Science. Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-22734-0_32.
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Hu, Guotun, Lin Du, and Xiaofeng Sun. "An Immersed Boundary Method for Simulating an Oscillating Airfoil." In Fluid-Structure-Sound Interactions and Control. Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-40371-2_49.
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Hoang, D. T. K., S. V. Pham, K. N. Tran, C. D. Nguyen, and K. P. Nguyen. "Aeroelastic Analysis on Wing Structure Using Immersed Boundary Method." In Proceedings of the International Conference on Advances in Computational Mechanics 2017. Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-10-7149-2_55.
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Zu, Wen-Hong, Ju-Hua Zhang, Duan-Duan Chen, Yuan-Qing Xu, Qiang Wei, and Fang-Bao Tian. "Immersed Boundary-Lattice Boltzmann Method for Biological and Biomedical Flows." In Communications in Computer and Information Science. Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/978-3-642-53962-6_34.
Full textConference papers on the topic "Immersed boundary method (IBM)"
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Prapamonthon, Prasert, Bo Yin, and Guowei Yang. "Extra-Low Reynolds Number Vane Separation Using Immersed Boundary Method." In ASME-JSME-KSME 2019 8th Joint Fluids Engineering Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/ajkfluids2019-5077.
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Abstract Nowadays, mini unmanned aerial vehicles (MUAVs) and micro air vehicles (MAVs) are not only beneficially used as aviation models but also as modern drones for military missions and other civilian applications. Hence, research and development of propulsion sources for MUAVs and MAVs dynamically increase with a future trend of high performance, but low energy consumption. Certainly, using micro and ultra-small-size gas turbine is a good option for the propulsion source. To achieve ideal flight of MUAVs and MAVs powered by micro and ultra-small-size gas turbines under this trend, understanding of flow phenomena at wide ranges of Reynolds number is essential. This research presents a 2D numerical study of characteristics of laminar flow separation and the trailing-edge vortex on a turbine vane at extra-low Reynolds numbers (Res) i.e. Re = 1800 and 3600, and three rotational angles (α) i.e. α = 0°, 15° and 30° using immersed boundary method (IBM). With this method, the problem of incompressible flow is addressed by a sharp interface IBM. Numerical results indicate that IBM can characterize phenomena of laminar separation flow, which usually happens on the turbine airfoil when laminar boundary layer cannot overcome adverse pressure gradients and viscous effects. To our current knowledge, this may be the first research to study flow behavior at such low Res for gas turbine vanes using IBM. Even though it is now not common to operate micro and ultra-small-size gas turbines under these conditions, it is important to know how aerodynamic performance may be if micro and ultra-small-size gas turbines need to run under such conditions in the near future.
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Tyagi, Mayank, and Sumanta Acharya. "Computation of Turbulent Flows in Complex and Moving Geometries Using Immersed Boundary Method." In ASME 2003 International Mechanical Engineering Congress and Exposition. ASMEDC, 2003. http://dx.doi.org/10.1115/imece2003-42839.
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A solution methodology for complex turbulent flows of industrial interests is developed using Immersed Boundary Method (IBM). IBM combines the efficiency inherent in using a fixed Cartesian grid to compute the fluid motion, along with the ease of tracking the immersed boundary at a set of moving Lagrangian points. IBM relies upon the body force terms added in the momentum equations to represents the complex geometry on a fixed Cartesian mesh. Resolution issues for turbulent flows can be addressed by Large Eddy Simulation (LES) technique provided an accurate and robust Subgrid Stress (SGS) model is available. Higher order of numerical accuracy schemes for turbulent flows can be maintained as well as the geometrical complexities can be rendered physically by combining LES with IBM. The proposed methodology is simple and ideally suited for the moving geometries involving no-slip walls with prescribed trajectories and locations. IBM is validated for the laminar flow past a heated cylinder in a channel and LES is validated for the turbulent lid-driven cavity flow. LES-IBM is then is used to render complex geometry of trapped vortex combustor to study fluid mixing inside trapped vortex cavity. To demonstrate the full potential of LES-IBM, a complex moving geometry problem of stator-rotor interaction is solved.
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Pan, Yu, Haibo Dong, and Wei Zhang. "An Improved Level-Set-Based Immersed Boundary Reconstruction Method for Computing Bio-Inspired Underwater Propulsion." In ASME 2021 Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/fedsm2021-65599.
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Abstract The immersed boundary method (IBM) has been widely employed to study bio-inspired underwater propulsion which often involves the high Reynolds number, complex body morphologies and large computational domain. Due to these problems, the immersed boundary (IB) reconstruction can be very costly in a simulation. Based on our previous work, an improved level-set-based immersed boundary method (LS-IBM) has been developed in this paper by introducing the narrow-band technique. Comparing with the previous LS-IBM, the narrowband level-set-based immersed boundary method (NBLS-IBM) is only required to propagate the level set values from the points near the boundaries to all the points in the narrow band. This improvement reduces the computational cost from O((LD/Δx)3) to O(k(LD/Δx)2). By simulating a steady-swimming Jackfish-like body, the consistency and stability of the new reconstruction method in the flow solver have been verified. Applications to a dolphin-like body swimming and a shark-like body swimming are used to demonstrate the efficiency and accuracy of the NBLS-IBM. The time for reconstructions shows that the reconstruction efficiency can increase up to 64.6% by using the NBLS-IBM while keeping the accuracy and robustness of the original LS-IBM. The vortex wake of the shark-like body in steady swimming shows the robustness, fastness and compatibility of the NBLS-IBM to our current flow solver.
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Oler, Adam M., Ning Zhang, and Steven R. Brandt. "Implementation of Infinite Height Levee in CaFunwave Using an Immersed Boundary Method." In ASME/JSME/KSME 2015 Joint Fluids Engineering Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/ajkfluids2015-34068.
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Numerical simulations of storm-surge-wave actions on coastal highways and levees are very important research topics for coastal Louisiana. In a large scale region hydrodynamic model, highways and levees are often complicated in geometry and much smaller in size compared to the grid size. The immersed boundary method (IBM) allows for those complicated geometries to be modeled in a less expensive way. It can allow very small geometries to be modeled in a large scale simulation, without requiring them to be explicitly on the grid. It can also allow for complicated geometries not collocated on the grid points. CaFunwave is a project that uses the Cactus Framework for modeling a solitary coastal wave impinging on a coastline, and is the wave solver in this research. The IBM allows for a levee with different geometries to be implemented on a simple Cartesian grid in the CaFunwave package. The IBM has not been used previously for this type of application. Implementing an infinite height levee using the IBM in the Cactus CaFunwave code involves introducing IB forcing terms into the standard 2-D depth averaged shallow water equation set. These forcing terms cause the 2-D solitary wave to experience a virtual force at the grid points surrounding the immersed boundary levee. In this paper the levee was implemented and tested using two different immersed boundary methods. The first method was a feedback-force method, which proved to be more effective at modeling the levee than the second method, the direct-forcing method. In this study, the results of the two methods, as well as the shape effects on the flow, are presented and discussed.
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Frisani, Angelo, and Yassin A. Hassan. "On the Immersed Boundary Method: Finite Element Versus Finite Volume Approach." In 2012 20th International Conference on Nuclear Engineering and the ASME 2012 Power Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/icone20-power2012-55082.
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A projection approach is presented for the coupled system of time-dependent incompressible Navier-Stokes equations in conjunction with the Immersed Boundary Method (IBM) for solving fluid flow problems in the presence of rigid objects not represented by the underlying mesh. The IBM allows solving the flow for geometries with complex objects without the need of generating a body fitted mesh. The no-slip boundary constraint is satisfied applying a boundary force at the immersed body surface. Using projection and interpolation operators from the fluid volume mesh to the solid surface mesh (i.e., the “immersed” boundary) and vice versa, it is possible to impose the extra constraint to the incompressible Navier-Stokes equations as a Lagrange multiplier in a fashion very similar to the effect pressure has on the momentum equations to satisfy the divergence-free constraint. The projection operation removes the immersed boundary surface slip and non-divergence-free components of the velocity field. The boundary force is determined implicitly at the inner iterations of the fractional step method implemented. No constitutive relations for the immersed boundary objects fluid interaction are required, allowing the formulation introduced to use larger CFL numbers compared to previous methodologies. An overview of the immersed boundary approach is presented showing third order accuracy in space and second order accuracy in time when the simulation results for the Taylor-Green decaying vortex are compared to the analytical solution using the Immersed Finite Element Method (IFEM). For the Immersed Finite Volume Method (IFVM) a ghost-cell approach is used. Second order accuracy in space and first order accuracy in time are obtained when the Taylor-Green decaying vortex test case is compared to the analytical solution. The numerical results are compared with the analytical solution also for adaptive mesh refinement (for the IFEM) showing an excellent error reduction. Computations were performed using IFEM and IFVM approaches for the time-dependent incompressible Navier-Stokes equations in a two-dimensional flow past a stationary circular cylinder at Re = 20, and 40, where shedding effects are not present. The drag coefficient and the recirculation length error compared to the experimental data is less than 3–4%. Simulations for the two-dimensional flow past a stationary circular cylinder at Re = 100 were also performed. For Re numbers above 46, unsteadiness generates vortex shedding, and an unsteady flow regime is present. The results shown are in excellent quantitative and qualitative agreement with the flow pattern expected. The numerical results obtained with the discussed IFEM and IFVM were also compared against other immersed boundary methodologies available in literature and simulation performed with the commercial computational fluid dynamics code STAR-CCM+/V5.02.009 for which a body fitted finite volume numerical discretization was used. The benchmark showed that the numerical results obtained with the implemented immersed boundary methods are very close to those obtained from STAR-CCM+ with a very fine mesh and in a good agreement with the other IBM techniques. The IBM based of finite element approach is numerically more accurate than the IBM based on finite volume discretization. In contrast, the latter is computationally more efficient than the former.
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Singh, Krishna M., Norihiko Nonaka, and U. Oh. "Immersed Boundary Method for CFD Analysis of Moving Boundary Problems in OpenFOAM." In ASME 2015 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/imece2015-53286.
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CFD simulation of hydraulic equipments involving moving boundary components is really challenging due to difficulty in maintaining a good quality mesh essential for obtaining accurate numerical solutions. To deal with these problems, commercial codes such as Ansys CFX provide the option of mesh morphing which must be used in conjunction with pre-defined multiple grid configurations to account for changing flow domain. In contrast to this approach, immersed boundary method (IBM) provides an attractive alternative in which the complex moving surface is immersed in a fixed Cartesian (or polyhedral) grid. We have developed an immersed boundary simulation tool-kit for moving boundary problems based on OpenFOAM. It requires the user to provide the definition of the immersed surfaces in STL (stereolithography) format, type of flow (internal/external) and motion (stationary, pre-defined or flow-induced) of the surface. Numerical simulations have been performed for selected test cases to assess the computational performance of the immersed boundary too-kit. Numerical results of flow over stationary as well as vibrating cylinders agree very well with available experimental and numerical results, and show that the immersed boundary simulations accurately capture the vortex shedding frequency and vortical structures for moving boundary problems.
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Yadav, Arun, and Ning Zhang. "Hydraulic Simulation for Calcasieu Lake Area With Small Rivers Using an Immersed Boundary Method." In ASME-JSME-KSME 2019 8th Joint Fluids Engineering Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/ajkfluids2019-4675.
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Abstract Coupled one-dimensional and two-dimensional hydraulic models using an immersed boundary method (IBM) was developed and implemented for a simple flooding case in a previously published study [1]. In this study, the IBM model was applied for simulations on a real geographical location, which was the Calcasieu Lake and its surrounding area in Southwest Louisiana. The simulation area ranges from the city of Lake Charles on the northern region to Gulf of Mexico on southern region, and two National Wildlife Refuges (NWR) on the east and west regions to the Calcasieu Lake. Calcasieu Lake is the major part of the wetland ecosystem, a simple change in the natural state of the lake, i.e. the change in the water surface elevation or flooding, can have a drastic impact on the ecosystem of its surrounding areas. The flooding to the wetlands is mainly through small rivers connected to the lake. In order to study the effects of coastal flooding to the wetlands, the IBM 1D-2D coupled model was implemented in the simulation package. The main purposes of this study are to: 1) determine the appropriate number of immersed boundary points to be used for this simulation, 2) validate the IBM model using an actual geographical region. Due to the lack of measurement in the small rivers, the validation was conducted by comparing simulated results from IBM model to the results from two non-IBM approaches (i.e., manually carved rivers and no rivers). Data obtained from NOAA and USGS were used for the boundary conditions for the 2D hydraulic model. During the first phase of study, the results from the higher number of immersed boundary points came close to each other which suggested that higher number of immersed boundary points are more precise for calculation. The final comparison of water surface elevation and velocity magnitude proved the accuracy and validity of the simulation package.
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He, Long, and Danesh Tafti. "Evaluating the Immersed Boundary Method in a Ribbed Duct for the Internal Cooling of Turbine Blades." In ASME Turbo Expo 2015: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/gt2015-43953.
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In this paper, immersed boundary method (IBM) is evaluated in a ribbed duct geometry to show the potential of simulating a complex geometry with a simple structured grid. In this framework, instead of resolving the geometry with a body conforming grid, the geometry is immersed into a volume background grid, and the immersed boundary cuts through the background grid and catches the geometry features. A fully developed rib roughed duct geometry is simulated with IBM at a bulk Reynolds number of 1.5 × 104. Three cases have been examined: a stationary case; a case of positive rotation at a rotation number (Ro = ΩDh/U) of 0.3 (destabilizing); and a case of negative rotation at Ro = −0.3 (stabilizing). The dynamic Smagorinsky subgird stress model is used with a second-order central difference discretization. Time averaged mean, turbulent quantities are presented, together with heat transfer. It is found that in general, the simulation with IBM resolves the bulk mean features of the flow with very good accuracy. In the stationary and positive rotation cases, the recirculation patterns and reattachment point predicted by IBM agree very well with the experiment data. In the negative rotation case, prediction of the recirculation zone shows some differences with the experiment. The IBM approach over predicts the turbulent statistics under destabilizing conditions. The overall good agreement between IBM and experimental results suggests that IBM is a promising method to apply to complex blade geometries.
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Oh, Tae Kyung, Danesh Tafti, and Krishnamurthy Nagendra. "LES-Conjugate Heat Transfer Analysis of a Ribbed Cooling Passage Using the Immersed Boundary Method." In ASME Turbo Expo 2019: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/gt2019-90397.
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Abstract The present study focuses on evaluating fully-coupled conjugate heat transfer simulation in a ribbed cooling passage with a fully developed flow assumption using LES with the immersed boundary method (IBM-LES-CHT). The IBM-LES and the IBM-CHT frameworks are validated prior to the main simulations by simulating purely convective heat transfer in the ribbed duct, and a laminar boundary layer flow over a 2D flat plate with heat conduction, respectively. For the main conjugate simulations, a ribbed duct geometry with a blockage ratio of 0.3 is simulated at a bulk Reynolds number of 10,000 with a conjugate boundary condition applied to the rib surface. The nominal Biot number is kept at 1, which is similar to the comparative experiment. As a means to overcome a large time scale disparity between the fluid and the solid regions, the use of a high artificial solid thermal diffusivity is compared to the physical diffusivity. It is shown that while the diffusivity impacts the instantaneous fluctuations in temperature, heat transfer and Nusselt numbers, it has an insignificantly small effect on the mean Nusselt number. Comparison between IBM-LES-CHT and iso-flux heat transfer simulations shows that the iso-flux case predicts higher local Nusselt numbers at the back face of the rib. Furthermore, the local Nusselt number augmentation ratio (EF) predicted by IBM-LES-CHT is compared to experiment and another LES conjugate simulation. Even though there is a mismatch between IBM-LES-CHT predictions and other two studies at the front face of the rib, the area-averaged EF compares reasonably well in other regions between IBM-LES-CHT prediction and the comparative studies.
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Ubald, Bryn N., Rob Watson, Jiahuan Cui, Paul Tucker, and Shahrokh Shahpar. "Application of Immersed Boundary Method on Instrumented Turbine Blade With LES." In ASME Turbo Expo 2020: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/gt2020-15423.
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Abstract Leading edge instrumentation used in compressor and turbine blades for jet-engine test rigs can cause significant obstruction and lead to a marked increase in downstream pressure loss. Typical instrumentation used in such a scenario could be a Kiel-shrouded probe with either a thermocouple or pitot-static tube for temperature/pressure measurement. High fidelity analysis of a coupled blade and probe requires the generation of a high quality mesh which can take a significant amount of an engineers time. The application of Immersed Boundary Method (IBM) and Large Eddy Simulation is shown in this paper to enable the use of an extremely simple mesh to observe the primary flow features generated due to the blade and probe interaction effects, as well as quantify downstream pressure loss to within a high level of accuracy. IBM is utilised to approximately model the probe, while fully resolving the blade itself through a series of LES simulations. This method has shown to be able to capture downstream loss profiles as well as integral quantities compared to both experiment and fully wall-resolved LES without the need to spend a significant amount of time generating the ideal mesh. Additionally, it is also able to capture the turbulence anisotropy surrounding the probe and blade regions.
Reports on the topic "Immersed boundary method (IBM)"
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Lundquist, Katherine Ann. Implementation of the Immersed Boundary Method in the Weather Research and Forecasting model. Office of Scientific and Technical Information (OSTI), 2006. http://dx.doi.org/10.2172/900883.
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Arthur, Robert S., Katherine A. Lundquist, and Jingyi Bao. Evaluating the performance of the immersed boundary method within the grey zone for improved weather forecasts in the HRRR model. Office of Scientific and Technical Information (OSTI), 2018. http://dx.doi.org/10.2172/1544937.
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