Relevant bibliographies by topics / Unstructured immersed boundary method

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  2. Dissertations / Theses
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Academic literature on the topic 'Unstructured immersed boundary method'

Author: Grafiati
Published: 4 June 2021
Last updated: 15 February 2022

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Journal articles on the topic "Unstructured immersed boundary method"

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Abalakin, I. V., A. P. Duben, N. S. Zhdanova, T. K. Kozubskaya, and L. N. Kudryavtseva. "Immersed Boundary Method on Deformable Unstructured Meshes for Airfoil Aeroacoustic Simulation." Computational Mathematics and Mathematical Physics 59, no. 12 (2019): 1982–93. http://dx.doi.org/10.1134/s0965542519120029.

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Abalakin, I. V., N. S. Zhdanova, and S. A. Soukov. "Reconstruction of body geometry on unstructured meshes by the immersed boundary method." Mathematical Models and Computer Simulations 9, no. 1 (2017): 83–91. http://dx.doi.org/10.1134/s2070048217010033.

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Ming, Ping-jian, Yang-zhe Sun, Wen-yang Duan, and Wen-ping Zhang. "Unstructured grid immersed boundary method for numerical simulation of fluid structure interaction." Journal of Marine Science and Application 9, no. 2 (2010): 181–86. http://dx.doi.org/10.1007/s11804-010-9078-9.

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Ouro, Pablo, Luis Cea, Luis Ramírez, and Xesús Nogueira. "An immersed boundary method for unstructured meshes in depth averaged shallow water models." International Journal for Numerical Methods in Fluids 81, no. 11 (2015): 672–88. http://dx.doi.org/10.1002/fld.4201.

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Martins, Diogo M. C., Duarte M. S. Albuquerque, and José C. F. Pereira. "On the use of polyhedral unstructured grids with a moving immersed boundary method." Computers & Fluids 174 (September 2018): 78–88. http://dx.doi.org/10.1016/j.compfluid.2018.07.010.

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Zhang, Yang, and Chunhua Zhou. "Reduction of Numerical Oscillations in Simulating Moving-Boundary Problems by the Local DFD Method." Advances in Applied Mathematics and Mechanics 8, no. 1 (2015): 145–65. http://dx.doi.org/10.4208/aamm.2014.m590.

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AbstractIn this work, the hybrid solution reconstruction formulation proposed by Luo et al. [H. Luo, H. Dai, P. F. de Sousa and B. Yin, On the numerical oscillation of the direct-forcing immersed-boundary method for moving boundaries, Computers & Fluids, 56 (2012), pp. 61–76] for the finite-difference discretization on Cartesian meshes is implemented in the finite-element framework of the local domain-free discretization (DFD) method to reduce the numerical oscillations in the simulation of moving-boundary flows. The reconstruction formulation is applied at fluid nodes in the immediate vicinity of the immersed boundary, which combines weightly the local DFD solution with the specific values obtained via an approximation of quadratic polynomial in the normal direction to the wall. The quadratic approximation is associated with the no-slip boundary condition and the local simplified momentum equation. The weighted factor suitable for unstructured triangular and tetrahedral meshes is constructed, which is related to the local mesh intervals near the immersed boundary and the distances from exterior dependent nodes to the boundary. Therefore, the reconstructed solution can account for the smooth movement of the immersed boundary. Several numerical experiments have been conducted for two- and three-dimensional moving-boundary flows. It is shown that the hybrid reconstruction approach can work well in the finite-element context and effectively reduce the numerical oscillations with little additional computational cost, and the spatial accuracy of the original local DFD method can also be preserved.
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Abalakin, I. V., N. S. Zhdanova, and T. K. Kozubskaya. "Immersed boundary method implemented for the simulation of an external flow on unstructured meshes." Mathematical Models and Computer Simulations 8, no. 3 (2016): 219–30. http://dx.doi.org/10.1134/s2070048216030029.

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Pan, Dartzi. "An Immersed Boundary Method on Unstructured Cartesian Meshes for Incompressible Flows with Heat Transfer." Numerical Heat Transfer, Part B: Fundamentals 49, no. 3 (2006): 277–97. http://dx.doi.org/10.1080/10407790500290709.

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Angelidis, Dionysios, Saurabh Chawdhary, and Fotis Sotiropoulos. "Unstructured Cartesian refinement with sharp interface immersed boundary method for 3D unsteady incompressible flows." Journal of Computational Physics 325 (November 2016): 272–300. http://dx.doi.org/10.1016/j.jcp.2016.08.028.

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Denaro, F. M., and F. Sarghini. "2-D transmitral flows simulation by means of the immersed boundary method on unstructured grids." International Journal for Numerical Methods in Fluids 38, no. 12 (2002): 1133–58. http://dx.doi.org/10.1002/fld.278.

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Dissertations / Theses on the topic "Unstructured immersed boundary method"

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Sekhar, Susheel Kumar. "Viscous hypersonic flow physics predictions using unstructured Cartesian grid techniques." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45857.

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Aerothermodynamics is an integral component in the design and implementation of hypersonic transport systems. Accurate estimates of the aerodynamic forces and heat transfer rates are critical in trajectory analysis and for payload weight considerations. The present work seeks to investigate the ability of an unstructured Cartesian grid framework in modeling hypersonic viscous flows. The effectiveness of modeling viscous phenomena in hypersonic flows using the immersed boundary ghost cell methodology of this solver is analyzed. The capacity of this framework to predict the surface physics in a hypersonic non-reacting environment is investigated. High velocity argon gas flows past a 2-D cylinder are simulated for a set of freestream conditions (Reynolds numbers), and impact of the grid cell sizes on the quality of the solution is evaluated. Additionally, the formulation is verified over a series of hypersonic Mach numbers for the flow past a hemisphere, and compared to experimental results and empirical estimates. Next, a test case that involves flow separation and the interaction between a hypersonic shock wave and a boundary layer, and a separation bubble is investigated using various adaptive mesh refinement strategies. The immersed boundary ghost cell approach is tested with two temperature clipping strategies, and their impact on the overall solution accuracy and smoothness of the surface property predictions are compared. Finally, species diffusion terms in the conservation equations, and collision cross-section based transport coefficients are installed, and hypersonic flows in thermochemical nonequilibrium environments are studied, and comparisons of the off-surface flow properties and the surface physics predictions are evaluated. First, a 2-D cylinder in a hypersonic reacting air flow is tested with an adiabatic wall boundary condition. Next, the same geometry is tested to evaluate the viscous chemistry prediction capability of the solver with an isothermal wall boundary condition, and to identify the strengths and weaknesses of the immersed boundary ghost cell methodology in computing convective heating rates in such an environment.
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de, Julien de Zelicourt Diane Alicia. "Pulsatile fontan hemodynamics and patient-specific surgical planning: a numerical investigation." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/39549.

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Single ventricle heart defects, where systemic and pulmonary venous returns mix in the single functional ventricle, represent the most complex form of congenital heart defect, affecting 2 babies per 1000 live births. Surgical repairs, termed "Fontan Repairs," reroute the systemic venous return directly to the pulmonary arteries, thus preventing venous return mixing and restoring normal oxygenation saturation levels. Unfortunately, these repairs are only palliative and Fontan patients are subjected to a multitude of chronic complications. It has long been suspected that hemodynamics play a role in determining patient outcome. However, the number of anatomical and functional variables that come into play and the inability to conduct large scale clinical evaluations, due to too small a patient population, has hindered decisive progress and there is still not a good understanding of the optimal care strategies on a patient-by-patient basis. Over the past decades, image-guided computational fluid dynamics (CFD) has arisen as an attractive option to accurately model such complex biomedical phenomena, providing a high degree of freedom regarding the geometry and flow conditions to be simulated, and carrying the potential to be automated for large sample size studies. Despite these theoretical advantages, few CFD studies have been able to account for the complexity of patient-specific anatomies and in vivo pulsatile flows. In this thesis, we develop an unstructured Cartesian immersed-boundary flow solver allowing for high resolution, time-accurate simulations in arbitrarily complex geometries, at low computational costs. Combining the proposed and validated CFD solver with an interactive virtual-surgery environment, we present an image-based surgical planning framework that: a) allows for in depth analysis of the pre-operative in vivo hemodynamics; b) enables surgeons to determine the optimum surgical scenario prior to the operation. This framework is first applied to retrospectively investigate the in vivo pulsatile hemodynamics of different Fontan repair techniques, and quantitatively compare their efficiency. We then report the prospective surgical planning investigations conducted for six failing Fontan patients with an interrupted inferior vena cava and azygous continuation. In addition to a direct benefit to the patients under consideration, the knowledge derived from these surgical planning studies will also have a larger impact for the clinical management of Fontan patients as they shed light onto the impact of caval offset, vessel flaring and other design parameters upon the Fontan hemodynamics depending on the underlying patient anatomy. These results provide useful surgical guidelines for each anatomical template, which could benefit the global surgical community, including centers that do not have access to patient-specific surgical planning interfaces.
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Billon, Laure. "Génération et adaptation de maillage volume-couche limite dynamique pour les écoulements turbulents autour de géométries complexes." Thesis, Paris Sciences et Lettres (ComUE), 2016. http://www.theses.fr/2016PSLEM077/document.

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La simulation numérique des écoulements turbulents en aérodynamique est très complexe. Elle consiste en l'étude de l'interaction entre un fluide et un profilimmergé. On observe à la surface du profil une zone de vitesse ralentie, nommée couche limite. L'étude fine de la couche limite est primordiale pour la résolution précise de l'écoulement. Elle nécessite de ce fait un maillage particulièrement fin et structuré. Nous proposons une procédure automatique permettant de générer un maillage adapté pour la résolution précise de la couche limite en accord avec la théorie et les caractéristiques physiques de l'écoulement. De plus, afin de décrire l'écoulement turbulent dans toute sa complexité à moindres coûts, nous proposons de combiner le maillage couche limite à une méthode d’adaptation de maillage dynamique.A cet effet, nous avons utilisé une version avancée de l'adaptation de maillagesur l'erreur a posteriori basée sur les arêtes et développé une méthode permettant à la fois de conserver la structure et le raffinement dans la couche limite mais également de décrire précisément les recirculations et le sillage. La nouvelle méthode d'adaptation volume-couche limite a été validée sur des cas2D et 3D à géométries complexes. Les résultats mettent en relief le potentiel decette approche et ouvre des perspectives intéressantes pour l'adaptation de maillage en mécanique des fluides<br>Numerical simulation of turbulent aerodynamics flows remains challenging. Such fluid-structure interaction problem involves generally a thin layer close to the wall where the fluid is slow down, called boundary layer. This latter requires a carefull study of the boundary layer since it is crucial regarding the accuracyof the complete flow computation. Therefore, a fine and structured mesh is needed close to the wall. In this work, we propose a novel automatic procedure to build a correct boundary layer mesh according to the theory and the flow parameters. Moreover, in order to describe exactly the behaviour of the flow on the whole domain, the boundary layer mesh is combined with a dynamic mesh adaptation method.It follows an advanced version of the edge based mesh adaptation method. Combined together, they ensure a fine and structured mesh in the boundarylayer while all the flow vortices are accurately resolved. This new method, called boundary-volume mesh adaptation, has been validated on several 2D and 3Dtest cases with complex geometries. Results emphasises the capacity ofthe approach and offer opportunities of improvement for numerical fluid mechanics mesh adaptation
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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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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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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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Gerych, Walter. "Versatile Anomaly Detection with Outlier Preserving Distribution Mapping Autoencoders." Digital WPI, 2019. https://digitalcommons.wpi.edu/etd-theses/1345.

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State-of-the-art deep learning methods for outlier detection make the assumption that outliers will appear far away from inlier data in the latent space produced by distribution mapping deep networks. However, this assumption fails in practice,because the divergence penalty adopted for this purpose encourages mapping outliers into the same high-probability regions as inliers. To overcome this shortcoming,we introduce a novel deep learning outlier detection method, called Outlier Preserving Distribution Mapping Autoencoder (OP-DMA), which succeeds to map outliers to low probability regions in the latent space of an autoencoder. For this we leverage the insight that outliers are likely to have a higher reconstruction error than inliers. We thus achieve outlier-preserving distribution mapping through weighting the reconstruction error of individual points by the value of a multivariate Gaussian probability density function evaluated at those points. This weighting implies that outliers will result in an overall penalty if they are mapped to low-probability regions. We show that if the global minimum of our newly proposed loss function is achieved,then our OP-DMA maps inliers to regions with a Mahalanobis distance less than \delta, and outliers to regions past this \delta, \delta being the inverse ChiSquared CDF evaluated at 1−\alpha with \alpha the percentage of outliers in the dataset. We evaluated OP-DMA on 11 benchmark real-world datasets and compared its performance against 7 different state-of-the-art outlier detection methods, including ALOCC and MO-GAAL. Our experiments show that OP-DMA outperforms the state-of-the-art methods on 7 of the datasets, and performs second best on 3 of the remaining 4 datasets, while no other method won on more than 1 dataset.
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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.
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Linnick, Mark Nicholas. "A high-order immersed boundary method for unsteady incompressible flow calculations." Diss., The University of Arizona, 2003. http://hdl.handle.net/10150/290009.

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A high-order immersed boundary method (IBM) for the computation of unsteady, incompressible fluid flows on two-dimensional, complex domains is proposed, analyzed, developed and validated. In the IBM, the equations of interest are discretized on a fixed Cartesian grid. As a result, domain boundaries do not always conform to the (rectangular) computational domain boundaries. This gives rise to 'immersed boundaries', i.e., boundaries immersed inside the computational domain. A new IBM is proposed to remedy problems in an older existing IBM that had originally been selected for use in numerical flow control investigations. In particular, the older method suffered from considerably reduced accuracy near the immersed boundary surface where sharp jumps in the solution, i.e., jump discontinuities in the function and/or its derivatives, were smeared out over several grid points. To avoid this behavior, a sharp interface method, originally developed by LeVeque & Li (1994) and Wiegmann & Bube (2000) in the context of elliptic PDEs, is introduced where the numerical scheme takes such discontinuities into consideration in its design. By comparing computed solutions to jump-singular PDEs having known analytical solutions, the new IBM is shown to maintain the formal fourth-order accuracy, in both time and space, of the underlying finite-difference scheme. Further validation of the new IBM code was accomplished through its application to several two-dimensional flows, including flow past a circular cylinder, and T-S waves in a flat plate boundary layer. Comparison of results from the new IBM with results available in the literature found good agreement in all cases.
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Books on the topic "Unstructured immersed boundary method"

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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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Atkins, H. L. Quadrature-free implementation of discontinuous Galerkin method for hyperbolic equations. National Aeronautics and Space Administration, Langley Research Center, 1996.

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Singh, K. P. 3-D unstructured method for flows past bodies in 6-DOF relative motion: Preprint from proceedings of 6th International Symposium of Computational Fluid Dynamics, Japan Society of Computational Fluid Dynamics, September 4-8, 1995, Lake Tahoe, Nevada. National Aeronautics and Space Administration, 1995.

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Frink, Neal T. Tetrahedral finite-volume solutions to the Navier-Stokes equations on complex configurations. National Aeronautics and Space Administration, Langley Research Center, 1998.

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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.

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V, Maddalon Dal, and Langley Research Center, eds. Assessment of an Euler-interacting boundary layer method using high Reynolds number transonic transport flight data. National Aeronautics and Space Administration, Langley Research Center, 1998.

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V, Maddalon Dal, and Langley Research Center, eds. Assessment of an Euler-interacting boundary layer method using high Reynolds number transonic transport flight data. National Aeronautics and Space Administration, Langley Research Center, 1998.

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Assessment of an Euler-interacting boundary layer method using high Reynolds number transonic transport flight data. National Aeronautics and Space Administration, Langley Research Center, 1998.

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V, Maddalon Dal, and Langley Research Center, eds. Assessment of an Euler-interacting boundary layer method using high Reynolds number transonic transport flight data. National Aeronautics and Space Administration, Langley Research Center, 1998.

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Book chapters on the topic "Unstructured immersed boundary method"

1

Abalakin, Ilya V., Tatiana K. Kozubskaya, Sergey A. Soukov, and Natalia S. Zhdanova. "Numerical Simulation of Flows over Moving Bodies of Complex Shapes Using Immersed Boundary Method on Unstructured Meshes." In Lecture Notes in Computational Science and Engineering. Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-23436-2_13.

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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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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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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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Conference papers on the topic "Unstructured immersed boundary method"

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Chou, Yi-Ju, and Oliver B. Fringer. "An Unstructured Immersed Boundary Method for Simulation of Flows over Bottom Topography." In Ninth International Conference on Estuarine and Coastal Modeling. American Society of Civil Engineers, 2006. http://dx.doi.org/10.1061/40876(209)33.

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Kozubskaya, T., L. Kudryavtseva, and V. Tsvetkova. "Unstructured Mesh Adaptation for Moving Bodies in Immersed Boundary Methods." In 14th WCCM-ECCOMAS Congress. CIMNE, 2021. http://dx.doi.org/10.23967/wccm-eccomas.2020.353.

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Sun, Lin, Sanjay R. Mathur, and Jayathi Y. Murthy. "An Unstructured Finite Volume Method for Incompressible Flows With Complex Immersed Boundaries." In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-12917.

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A numerical method is developed for solving the 3D, unsteady, incompressible flows with immersed moving solids of arbitrary geometrical complexity. A co-located (non-staggered) finite volume method is employed to solve the Navier-Stokes governing equations for flow region using arbitrary convex polyhedral meshes. The solid region is represented by a set of material points with known position and velocity. Faces in the flow region located in the immediate vicinity of the solid body are marked as immersed boundary (IB) faces. At every instant in time, the influence of the body on the flow is accounted for by reconstructing implicitly the velocity the IB faces from a stencil of fluid cells and solid material points. Specific numerical issues related to the non-staggered formulation are addressed, including the specification of face mass fluxes, and corrections to the continuity equation to ensure overall mass balance. Incorporation of this immersed boundary technique within the framework of the SIMPLE algorithm is described. Canonical test cases of laminar flow around stationary and moving spheres and cylinders are used to verify the implementation. Mesh convergence tests are carried out. The simulation results are shown to agree well with experiments for the case of micro-cantilevers vibrating in a viscous fluid.
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Iaccarino, Gianluca, Sangjin Lee, Jungchan Kim, and Youngho Ju. "Towards a Flexible Immersed Boundary Method for Fluid/Structure Interactions in Turbomachinery Applications." In ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/gt2016-56801.

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The Immersed Boundary method is implemented in an unstructured-grid, compressible Reynolds averaged Navier-Stokes solver to perform fluid/structure interaction simulations in a turbo machinery configurations. The implementation enables the use of locally refined meshes and general streamlined grids to capture highly curved components and non-Cartesian configurations typical of turbomachinery components. The coupling between fluid solver and a stand-alone structure based solver is based on a fully implicit procedure and is validated by comparisons to existing results on simple rigid and deformable cylinders configurations. Initial applications of the method to aeroelastic computations of the NASA Rotor 67 configuration are also reported.
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Huang, Wei-Xi, Cheong Bong Chang, and Hyung Jin Sung. "An Improved Penalty Immersed Boundary Method for Fluid-Flexible Body Interaction." In ASME-JSME-KSME 2011 Joint Fluids Engineering Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/ajk2011-20006.

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An improved penalty immersed boundary (pIB) method has been proposed for simulation of fluid-flexible body interaction problems. In the proposed method, the fluid motion is defined on the Eulerian domain, while the solid motion is described by the Lagrangian variables. To account for the interaction, the flexible body is assumed to be composed of two parts: massive material points and massless material points, which are assumed to be linked closely by a stiff spring with damping. The massive material points are subjected to the elastic force of solid deformation but do not interact with the fluid directly, while the massless material points interact with the fluid by moving with the local fluid velocity. The flow solver and the solid solver are coupled in this framework and are developed separately by different methods. The fractional step method is adopted to solve the incompressible fluid motion on a staggered Cartesian grid, while the finite element method is developed to simulate the solid motion using an unstructured triangular mesh. The interaction force is just the restoring force of the stiff spring with damping, and is spread from the Lagrangian coordinates to the Eulerian grids by a smoothed approximation of the Dirac delta function. In the numerical simulations, three-dimensional simulations of fluid-flexible body interaction are carried out, including deformation of a spherical capsule in a linear shear flow. A comparison between the numerical results and the theoretical solutions is presented.
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Kozubskaya, Tatiana, Ilya Abalakin, Alexey Duben, Andrey Gorobets, and Natalia Zhdanova. "Numerical Simulation of Slat Noise of High-Lift Devices Using Immersed Boundary Method on Unstructured Meshes." In 25th AIAA/CEAS Aeroacoustics Conference. American Institute of Aeronautics and Astronautics, 2019. http://dx.doi.org/10.2514/6.2019-2461.

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Zacharzewski, Piotr, and Richard Jefferson-Loveday. "Implicit GPU Accelerated Numerical Simulations via the Use of Ghost Cell Immersed Boundary Method." In ASME Turbo Expo 2020: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/gt2020-15844.

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Abstract Flow as well as geometry inside turbomachinery components such as turbine blades is complex and difficult to handle accurately. Computationally affordable Reynolds Averaged Navier Stokes (RANS) simulations are often not suitable and partly resolving simulations such as Large Eddy Simulation (LES) or hybrid RANS-LES are needed for sufficient accuracy in the area. Within industrial turbine design, these are not deployed routinely, if at all, due to their presently unaffordable computational cost and time-consuming grid generation for complex geometries. General Purpose Graphic Processing Units (GPGPUs) and other modern heterogeneous hardware offer much cheaper computational power, however, so far remain mostly unharnessed in the field of CFD due to difficulty of creating structured datasets required to utilise the GPUs effectively. While unstructured or hybrid grids can be used on massively parallel platforms, the typically irregular memory access patterns they demand usually prohibits effective scaling and GPU remains mostly idle, negating the benefits. Within CFD, structured datasets with ordered memory access patterns are most easily obtained with structured multiblock grids and such grids are an excellent candidate for GPU platforms. This is not without challenges as creating high quality structured grids over complex geometries is known to be a highly time consuming and difficult process. Another limitation of GPUs is difficulty of solving tridiagonal systems of equations efficiently on those platforms. Solution of such systems of equations is typically required for implicit time advancement or convergence acceleration techniques such as AMG and it is well established that implicit numerical schemes provide significant computational savings due to their efficiency. In the present work a novel Alternating Direction Implicit (ADI) library is integrated into the CFD system to enable scalable solution of tridiagonal systems on GPUs. In the current paper a GPU-accelerated Immersed Boundary Method (IBM) code is presented and validated for turbo-machinery applications. It is shown that the combination of IBM, a high-level Oxford Parallel library for Structured applications (OPS) and an ADI solver provide the geometric as well as computational flexibility unmatched by traditional unstructured solvers. A single source code exists for major hardware platforms and the parallel implementation is decoupled from the scientific codebase, making the code scalable and easily adaptable to any emerging, future architectures.
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Seto, Mae L., Rubens Campregher, Stefan Murphy, and Julio Militzer. "Prediction of Ship Acoustic Signature Due to Fluid Flow." In ASME 2007 International Mechanical Engineering Congress and Exposition. ASMEDC, 2007. http://dx.doi.org/10.1115/imece2007-43343.

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The contribution of flow noise to the radiated acoustic signature of CFAV Quest is of interest. Quest is the research ship used by Defence R&amp;D Canada as a quiet platform. It is difficult to identify the flow noise component in an acoustic ranging so there is interest in predicting the flow noise as a first step towards extracting it from range measurements. Below propulsor cavitation inception speeds, machinery-induced noise dominates. While flow noise does not usually dominate in the presence of machinery-induced noise or propulsor cavitation, it is unclear what fraction of the total noise power flow noise constitutes. A direct numerical simulation for a complex ship geometry was impractical so an alternative approach was sought. An immersed boundary method was used to model the presence of the ship in the flow domain. The unsteady flow field was calculated using a finite volume method over an unstructured Cartesian grid. The flow field around Quest in straight and level flight was calculated at Reynolds numbers between 1.8×108 and 4.3×108, corresponding to a full-scale speed range of 4 to 10 knots. Results from such flow field predictions become the hydrodynamic sources in the integrals of Lighthill’s acoustic analogy to predict the far-field acoustic signature from the flow past the hull. These far-field predictions consist of computing the propagation and radiation of the hydrodynamic sources. This assumes noise generation and its propagation are decoupled. Under certain circumstances, knowledge of the predicted flow component helps to extract it from a standard acoustic ranging.
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Arina, Renzo, and Bijan Mohammadi. "An Immersed Boundary Method for Aeroacoustics Problems." In 14th AIAA/CEAS Aeroacoustics Conference (29th AIAA Aeroacoustics Conference). American Institute of Aeronautics and Astronautics, 2008. http://dx.doi.org/10.2514/6.2008-3003.

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Keistler, Patrick. "An Immersed Boundary Method for Supersonic Flow." In 46th AIAA Aerospace Sciences Meeting and Exhibit. American Institute of Aeronautics and Astronautics, 2008. http://dx.doi.org/10.2514/6.2008-529.

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Reports on the topic "Unstructured immersed boundary method"

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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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England, William, and Jeffrey Allen. Thermal, microchannel, and immersed boundary extension validation for the Lattice-Boltzmann method : Report 2 in “discrete nano-scale mechanics and simulations” series. Information Technology Laboratory (U.S.), 2017. http://dx.doi.org/10.21079/11681/22863.

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