Academic literature on the topic 'Volume of Fluid (VOF) method'
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Journal articles on the topic "Volume of Fluid (VOF) method"
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KUMAR, BIPIN, MARTIN CRANE, and YAN DELAURÉ. "ON THE VOLUME OF FLUID METHOD FOR MULTIPHASE FLUID FLOW SIMULATION." International Journal of Modeling, Simulation, and Scientific Computing 04, no. 02 (2013): 1350002. http://dx.doi.org/10.1142/s1793962313500025.
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Numerical study of multiphase fluid flows require mathematical methods for distinguishing interface between two fluids. The volume of fluid (VOF) method is one of such method which takes care of fluid shape in a local domain and reconstructs the interface from volume fraction of one fluid. Maintaining sharp interface during reconstruction is a challenging task and geometrical approach of VOF method better suits for incompressible fluids. This paper provides a complete mathematical discussion of extended form of VOF method using a approach known as piecewise linear interface calculation (PLIC). An analytical relation between volume fraction and interface position has been explored with the help of primitive geometrical shapes. The method with this analytical relation has been applied to multiphase fluid flow benchmark problems and found to be in good agreement.
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Sham Bansal, Ishu Goyal. "Tracking Fluid-Fluid Interface In Microchannels Using The Volume Of Fluid Method." Nanotechnology Perceptions 20, no. 1 (2024): 244–57. https://doi.org/10.62441/nano-ntp.v20i1.5307.
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The current research investigates the two-phase flow of immiscible fluids passing a cylindrical obstruction. Numerical simulations were conducted using Ansys Fluent 17.0 to characterize the resulting flow patterns. The liquid-liquid interface was tracked using the Volume of Fluid (VOF) technique. The VOF multiphase flow model is effective in predicting the global behavior of liquid-liquid two-phase flows. In this work, two immiscible liquids with varying viscosities were made to flow adjacently in separate phases. The observed flow patterns were correlated with the Capillary and Reynolds numbers. The relatively low values of these parameters indicate a laminar flow regime where viscous forces and interfacial tension dictate the interface morphology. As a result, gravitational effects were deemed insignificant in this study, as the dominant forces within the model are viscous and surface tension forces. The results indicate a tendency for the more viscous fluid to move towards the less viscous fluid under the influence of viscous pressure, especially in the vicinity of the interface and on the surface of micro-particles, which are invariably surrounded by the liquid with higher viscosity.
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Ii, Satoshi, Xiaobo Gong, Kazuyasu Sugiyama, Jinbiao Wu, Huaxiong Huang, and Shu Takagi. "A Full Eulerian Fluid-Membrane Coupling Method with a Smoothed Volume-of-Fluid Approach." Communications in Computational Physics 12, no. 2 (2012): 544–76. http://dx.doi.org/10.4208/cicp.141210.110811s.
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AbstractA novel full Eulerian fluid-elastic membrane coupling method on the fixed Cartesian coordinate mesh is proposed within the framework of the volume-of-fluid approach. The present method is based on a full Eulerian fluid-(bulk) structure coupling solver (Sugiyama et al., J. Comput. Phys., 230 (2011) 596-627), with the bulk structure replaced by elastic membranes. In this study, a closed membrane is consid-ered, and it is described by a volume-of-fluid or volume-fraction information generally called VOF function. A smoothed indicator (or characteristic) function is introduced as a phase indicator which results in a smoothed VOF function. This smoothed VOF function uses a smoothed delta function, and it enables a membrane singular force to be incorporated into a mixture momentum equation. In order to deal with a membrane deformation on the Eulerian mesh, a deformation tensor is introduced and updated within a compactly supported region near the interface. Both the neo-Hookean and the Skalak models are employed in the numerical simulations. A smoothed (and less dissipative) interface capturing method is employed for the advection of the VOF function and the quantities defined on the membrane. The stability restriction due to membrane stiffness is relaxed by using a quasi-implicit approach. The present method is validated by using the spherical membrane deformation problems, and is applied to a pressure-driven flow with the biconcave membrane capsules (red blood cells).
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Shang, Zhi, Jing Lou, and Hongying Li. "Simulations of Flow Transitions in a Vertical Pipe Using Coupled Level Set and VOF Method." International Journal of Computational Methods 14, no. 02 (2017): 1750013. http://dx.doi.org/10.1142/s021987621750013x.
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The level set (LS) and volume-of-fluid (VOF) methods are usually employed to simulate the two-phase flow. However every single method of them will face the mass conservative or accurate issues during the simulation. The coupled level set and volume-of-fluid (CLSVOF) method was not only able to conquer the shortages of the LS and VOF methods but also simultaneously keep the merits of both of the methods. In CLSVOF method the geometry reconstruction technology was employed to realize the coupling between LS and VOF. After the validation of single bubble rising cases, the CLSVOF method was used to simulate the complex transitional two-phase flows in a vertical pipe and the simulation results were compared to experiments.
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Cheng, Hongping. "Application of Motion Interface Tracking CVOFLS Method to Zalesak Disk Problem." Highlights in Science, Engineering and Technology 35 (April 11, 2023): 105–8. http://dx.doi.org/10.54097/hset.v35i.7041.
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The interface curvature calculation is not accurate in VOF method and the interface mass is not conserved in Level Set method, A new interface tracking method CVOFLS is proposed (Coupled Volume of Fluid and Level Set method). This method combines the advantages of VOF and Level Set, The VOF and Level Set functions are simultaneously solved according to the fluid velocity, The interface obtained by the VOF function is used to correct the fluid quality, The Level Set function is used to calculate the interface norma, The Level Set function reinitialization process is omitted, Thus, the deficiencies of the two methods are overcome effectively. An example of interface tracking numerical simulation shows that, this method can guarantee high precision of free interface tracking and good mass conservation, and it can improve the calculation efficiency.
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Cui, Liying, Yingge Yang, and Cuiping Ren. "Application of CVOFLS method in multi vortex shear flow field." Journal of Physics: Conference Series 2441, no. 1 (2023): 012034. http://dx.doi.org/10.1088/1742-6596/2441/1/012034.
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Abstract Coupled Volume of Fluid and Level Set method inherits the advantages of VOF and Level Set methods, takes VOF function as the main body to simulate the fluid motion interface, and corrects the normal direction of the interface through Level Set function, so as to effectively overcome the shortcomings of the two methods. The numerical simulation example of multi vortex shear flow field shows that this method can ensure better simulation accuracy of moving interface and higher calculation efficiency.
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Ketabdari, M. J., and H. Saghi. "A Novel Algorithm of Advection Procedure in Volume of Fluid Method to Model Free Surface Flows." ISRN Applied Mathematics 2012 (April 3, 2012): 1–16. http://dx.doi.org/10.5402/2012/521012.
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In this study, the developed procedure of advection in volume of fluid (VOF) method is presented for free surface modeling. The fluid is assumed to be incompressible and viscous and therefore, Navier-Stokes and continuity are considered as governing equations. Applying Youngs’ algorithm in staggered grids, it is assumed that fluid particles in the cell have the same velocity of the cell faces. Therefore, fluxes to neighboring cells are estimated based on cell face velocities. However, these particles can show different velocities between two adjacent cell faces. In developed model, the velocity in mass center of fluid cell is evaluated to calculate fluxes from cell faces. The performance of the model is evaluated using some alternative schemes such as translation, rotation, shear test, and dam break test. These tests showed that the developed procedure improves the results when using coarse grids. Therefore, the Modified Youngs-VOF (MYV) method is suggested as a new VOF algorithm which models the free surface problems more accurately.
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Chen, Gujun, Qiangqiang Wang, and Shengping He. "Assessment of an Eulerian multi-fluid VOF model for simulation of multiphase flow in an industrial Ruhrstahl–Heraeus degasser." Metallurgical Research & Technology 116, no. 6 (2019): 617. http://dx.doi.org/10.1051/metal/2019049.
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An Eulerian multi-fluid VOF model, the coupling of the Eulerian model and the “VOF” interface tracking method, offered by ANSYS Fluent has been first applied to investigate the complex multiphase flow in an industrial Ruhrstahl–Heraeus (RH) degasser. The idea of this study is to use the Eulerian model in the regions of the domain where the argon bubbles are dispersed in molten steel; in the regions of the domain where the sharp interfaces between the steel and slag or argon are of interest, the “VOF” method is adopted. The calculated flow characteristic, mixing time and circulation flow rate of molten steel in the RH degasser agree well with the observations reported in literature. Compared with the widely accepted Eulerian method and the discrete phase model–volume of fluid (DPM–VOF) coupled method, the Eulerian multi-fluid VOF model demonstrates the suitability for modeling the multiphase flow in the RH degasser where both dispersed and sharp interfaces are present.
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Rossano, Viola, and Giuliano De Stefano. "Hybrid VOF–Lagrangian CFD Modeling of Droplet Aerobreakup." Applied Sciences 12, no. 16 (2022): 8302. http://dx.doi.org/10.3390/app12168302.
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A hybrid VOF–Lagrangian method for simulating the aerodynamic breakup of liquid droplets induced by a traveling shock wave is proposed and tested. The droplet deformation and fragmentation, together with the subsequent mist development, are predicted by using a fully three-dimensional computational fluid dynamics model following the unsteady Reynolds-averaged Navier–Stokes approach. The main characteristics of the aerobreakup process under the shear-induced entrainment regime are effectively reproduced by employing the scale-adaptive simulation method for unsteady turbulent flows. The hybrid two-phase method combines the volume-of-fluid technique for tracking the transient gas–liquid interface on the finite volume grid and the discrete phase model for following the dynamics of the smallest liquid fragments. The proposed computational approach for fluids engineering applications is demonstrated by making a comparison with reference experiments and high-fidelity numerical simulations, achieving acceptably accurate results without being computationally expensive.
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Qiu, Ruofan, Anlin Wang, Qiwei Gong, and Tao Jiang. "Simulation of two-phase fluid mixture flow in rectangular two-inlet cavity using lattice Boltzmann method." International Journal of Modern Physics C 25, no. 04 (2014): 1450004. http://dx.doi.org/10.1142/s0129183114500041.
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In this paper, two-phase fluid mixture flow in rectangular two-inlet cavity is studied using lattice Boltzmann method (LBM). To simulate two-phase fluids with large viscosity difference, the pseudo-potential model is improved. The improved model is verified for surface tension through Laplace's law and shown much better performance in simulating fluids with large viscosity difference than pseudo-potential model. The multiple-relaxation-time (MRT) scheme is used to enhance numerical stability. Then the two-phase fluid mixture flow with same and different viscosity in two-inlet cavity is simulated by present lattice Boltzmann (LB) model, pseudo-potential LB model and volume-of-fluid (VOF) method, respectively. The comparison of these numerical results shows that LB model is more suitable for such kind of flow than VOF method, since it can reflect repulsive forces and transitional region of two-phase fluids in dynamic process. Moreover, it also shows that present LB model has better dynamic stability than pseudo-potential model. Furthermore, simulations of the two-phase fluid mixture flow with different fluid viscosities, inlet velocities, inlet heights and outlet positions using present LB model are presented, exhibiting their effect to contact area of fluids.
Dissertations / Theses on the topic "Volume of Fluid (VOF) method"
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Maini, Deepak. "VOF Based Multiphase Lattice Boltzmann Method Using Explicit Kinematic Boundary Conditons at the Interface." Thesis, Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/16240.
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A VOF based multiphase Lattice Boltzmann method that explicitly prescribes kinematic boundary conditions at the interface is developed. The advantage of the method is the direct control over the surface tension value. The details of the numerical method are presented. The Saffman instability, Taylor instability, and flow of deformable suspensions in a channel are used as example-problems to demonstrate the accuracy of the method. The method allows for relatively large viscosity and density ratios.
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Schmidtke, Martin. "Untersuchung der Dynamik fluider Partikel auf Basis der Volume of Fluid Methode." Forschungszentrum Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-27925.
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Die in dieser Arbeit vorgestellten Simulationen aufsteigender fluider Partikel wurden mit dem CFD-Programm FS3D durchgeführt, welches auf der Volume-of-Fluid (VoF) Methode basiert. Die Validierung des Codes erfolgt durch Vergleich der numerischen Lösungen für schleichende Strömungen mit analytischen Lösungen, wobei eine gute Übereinstimmung festgestellt wird. Im ersten Teil der Dissertation werden Simulationen für den freien Aufstieg von Öltropfen in Wasser mit experimentellen Beobachtungen hinsichtlich der Aufstiegsgeschwindigkeit, der Tropfenform und der Bewegungsbahn verglichen. Die Aufstiegsgeschwindigkeiten und Widerstandsbeiwerte sind vergleichbar, die simulierten Tropfen sind jedoch deutlich flacher. Dieser Unterschied kann durch Verunreinigungen der Grenzfläche im Experiment verursacht sein. Der Übergang von einem gradlinigen Aufstieg zu zickzack-förmigen Aufstiegsbahnen kann mit Hilfe der Simulationen auf Instabilitäten im Nachlauf der Blasen zurückgeführt werden, die zu einer periodischen Wirbelablösung führen. Im zweiten Teil der Dissertation wird der Aufstieg von Blasen in linearen Scherströmungen untersucht. Steigen die Blasen in einer vertikalen Scherströmung auf, so beobachtet man eine seitliche Migration. Diese seitliche Migration der Blasen wird durch die sogenannte Liftkraft verursacht, deren Vorzeichen und Betrag von der Blasengröße und den Stoffeigenschaften der Flüssigkeit abhängt. Die Simulationen zeigen, daß das Vorzeichen der Liftkraft für eher sphärische Blasen durch den Bernoulli-Effekt erklärt werden kann. An stark deformierten Blasen hingegen wirkt die Liftkraft in umgekehrter Richtung. Dieses Phänomen tritt auch in den Simulationen auf. Verschiedene Hypothesen für die Ursache dieses Phänomens werden überprüft. Die bekannteste experimentelle Korrelation für die Liftkraft von Tomiyama u.a. (2002) wird durch Simulation von realen Flüssigkeiten mit bekannten Stoffeigenschaften wie auch von Modellfluiden mit willkürlichen Stoffeigenschaften validiert und weitgehend bestätigt. Die Lift-Korrelation hat demnach hinsichtlich der Stoffeigenschaften der Flüssigkeit einen größeren Geltungsbereich, als bisher experimentell überprüft wurde. The simulations presented in this thesis were performed with the CFD code FS3D which is based on the Volume of Fluid method. The code is validated using analytical solutions for creeping flows and a good agreement is observed between simulation and analytical solution. In the first part of the thesis, the free rise of oil drops in water is simulated and compared with experimental observations. The results show that the rising velocities and the drag coefficients are similar in both cases, but the simulated drops are flatter (more oblate). This difference may be caused by impurities of the particle surface (surfactants) in the experiments. The simulations show that the transition from rectilinear to periodic trajectories is caused by instabilities in the wake, which lead to a periodic vortex shedding. In the second part of the thesis, the rise of bubbles in linear shear flows is investigated. If bubbles rise in a vertical shear flow, a lateral migration can be observed. This migration is caused by the so called lift force. Sign and magnitude of the lift force depend on the size of the bubble and the material properties of the liquid. The simulation results show that the sign of the lift force on spherical bubbles can be explained by the Bernoulli effect. However, the lift force on more distorted bubbles acts in the opposite direction. This phenomenon can also be observed in the simulation. In this work several hypotheses for the reason of this phenomenon are checked. Furthermore, most common correlation for the lift force (developed by Tomiyama et al. in 2002) is validated for fluids of known material and model fluids with arbitrary material data. The correlation is valid in a wider range of fluid material properties than proved experimentally up to now.
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Schmidtke, Martin. "Untersuchung der Dynamik fluider Partikel auf Basis der Volume of Fluid Methode." Forschungszentrum Dresden-Rossendorf, 2008. https://hzdr.qucosa.de/id/qucosa%3A21619.
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Die in dieser Arbeit vorgestellten Simulationen aufsteigender fluider Partikel wurden mit dem CFD-Programm FS3D durchgeführt, welches auf der Volume-of-Fluid (VoF) Methode basiert. Die Validierung des Codes erfolgt durch Vergleich der numerischen Lösungen für schleichende Strömungen mit analytischen Lösungen, wobei eine gute Übereinstimmung festgestellt wird. Im ersten Teil der Dissertation werden Simulationen für den freien Aufstieg von Öltropfen in Wasser mit experimentellen Beobachtungen hinsichtlich der Aufstiegsgeschwindigkeit, der Tropfenform und der Bewegungsbahn verglichen. Die Aufstiegsgeschwindigkeiten und Widerstandsbeiwerte sind vergleichbar, die simulierten Tropfen sind jedoch deutlich flacher. Dieser Unterschied kann durch Verunreinigungen der Grenzfläche im Experiment verursacht sein. Der Übergang von einem gradlinigen Aufstieg zu zickzack-förmigen Aufstiegsbahnen kann mit Hilfe der Simulationen auf Instabilitäten im Nachlauf der Blasen zurückgeführt werden, die zu einer periodischen Wirbelablösung führen. Im zweiten Teil der Dissertation wird der Aufstieg von Blasen in linearen Scherströmungen untersucht. Steigen die Blasen in einer vertikalen Scherströmung auf, so beobachtet man eine seitliche Migration. Diese seitliche Migration der Blasen wird durch die sogenannte Liftkraft verursacht, deren Vorzeichen und Betrag von der Blasengröße und den Stoffeigenschaften der Flüssigkeit abhängt. Die Simulationen zeigen, daß das Vorzeichen der Liftkraft für eher sphärische Blasen durch den Bernoulli-Effekt erklärt werden kann. An stark deformierten Blasen hingegen wirkt die Liftkraft in umgekehrter Richtung. Dieses Phänomen tritt auch in den Simulationen auf. Verschiedene Hypothesen für die Ursache dieses Phänomens werden überprüft. Die bekannteste experimentelle Korrelation für die Liftkraft von Tomiyama u.a. (2002) wird durch Simulation von realen Flüssigkeiten mit bekannten Stoffeigenschaften wie auch von Modellfluiden mit willkürlichen Stoffeigenschaften validiert und weitgehend bestätigt. Die Lift-Korrelation hat demnach hinsichtlich der Stoffeigenschaften der Flüssigkeit einen größeren Geltungsbereich, als bisher experimentell überprüft wurde. The simulations presented in this thesis were performed with the CFD code FS3D which is based on the Volume of Fluid method. The code is validated using analytical solutions for creeping flows and a good agreement is observed between simulation and analytical solution. In the first part of the thesis, the free rise of oil drops in water is simulated and compared with experimental observations. The results show that the rising velocities and the drag coefficients are similar in both cases, but the simulated drops are flatter (more oblate). This difference may be caused by impurities of the particle surface (surfactants) in the experiments. The simulations show that the transition from rectilinear to periodic trajectories is caused by instabilities in the wake, which lead to a periodic vortex shedding. In the second part of the thesis, the rise of bubbles in linear shear flows is investigated. If bubbles rise in a vertical shear flow, a lateral migration can be observed. This migration is caused by the so called lift force. Sign and magnitude of the lift force depend on the size of the bubble and the material properties of the liquid. The simulation results show that the sign of the lift force on spherical bubbles can be explained by the Bernoulli effect. However, the lift force on more distorted bubbles acts in the opposite direction. This phenomenon can also be observed in the simulation. In this work several hypotheses for the reason of this phenomenon are checked. Furthermore, most common correlation for the lift force (developed by Tomiyama et al. in 2002) is validated for fluids of known material and model fluids with arbitrary material data. The correlation is valid in a wider range of fluid material properties than proved experimentally up to now.
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Koebe, Mario. "Numerische Simulation aufsteigender Blasen mit und ohne Stoffaustausch mittels der volume of fluid (VOF) Methode." [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=973222484.
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Peña, Monferrer Carlos. "Computational fluid dynamics multiscale modelling of bubbly flow. A critical study and new developments on volume of fluid, discrete element and two-fluid methods." Doctoral thesis, Universitat Politècnica de València, 2017. http://hdl.handle.net/10251/90493.
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The study and modelling of two-phase flow, even the simplest ones such as the bubbly flow, remains a challenge that requires exploring the physical phenomena from different spatial and temporal resolution levels. CFD (Computational Fluid Dynamics) is a widespread and promising tool for modelling, but nowadays, there is no single approach or method to predict the dynamics of these systems at the different resolution levels providing enough precision of the results. The inherent difficulties of the events occurring in this flow, mainly those related with the interface between phases, makes that low or intermediate resolution level approaches as system codes (RELAP, TRACE, ...) or 3D TFM (Two-Fluid Model) have significant issues to reproduce acceptable results, unless well-known scenarios and global values are considered. Instead, methods based on high resolution level such as Interfacial Tracking Method (ITM) or Volume Of Fluid (VOF) require a high computational effort that makes unfeasible its use in complex systems.
In this thesis, an open-source simulation framework has been designed and developed using the OpenFOAM library to analyze the cases from microescale to macroscale levels. The different approaches and the information that is required in each one of them have been studied for bubbly flow. In the first part, the dynamics of single bubbles at a high resolution level have been examined through VOF. This technique has allowed to obtain accurate results related to the bubble formation, terminal velocity, path, wake and instabilities produced by the wake. However, this approach has been impractical for real scenarios with more than dozens of bubbles. Alternatively, this thesis proposes a CFD Discrete Element Method (CFD-DEM) technique, where each bubble is represented discretely. A novel solver for bubbly flow has been developed in this thesis. This includes a large number of improvements necessary to reproduce the bubble-bubble and bubble-wall interactions, turbulence, velocity seen by the bubbles, momentum and mass exchange term over the cells or bubble expansion, among others. But also new implementations as an algorithm to seed the bubbles in the system have been incorporated. As a result, this new solver gives more accurate results as the provided up to date.
Following the decrease on resolution level, and therefore the required computational resources, a 3D TFM have been developed with a population balance equation solved with an implementation of the Quadrature Method Of Moments (QMOM). The solver is implemented with the same closure models as the CFD-DEM to analyze the effects involved with the lost of information due to the averaging of the instantaneous Navier-Stokes equation. The analysis of the results with CFD-DEM reveals the discrepancies found by considering averaged values and homogeneous flow in the models of the classical TFM formulation. Finally, for the lowest resolution level approach, the system code RELAP5/MOD3 is used for modelling the bubbly flow regime. The code has been modified to reproduce properly the two-phase flow characteristics in vertical pipes, comparing the performance of the calculation of the drag term based on drift-velocity and drag coefficient approaches.<br>El estudio y modelado de flujos bifásicos, incluso los más simples como el bubbly flow, sigue siendo un reto que conlleva aproximarse a los fenómenos físicos que lo rigen desde diferentes niveles de resolución espacial y temporal. El uso de códigos CFD (Computational Fluid Dynamics) como herramienta de modelado está muy extendida y resulta prometedora, pero hoy por hoy, no existe una única aproximación o técnica de resolución que permita predecir la dinámica de estos sistemas en los diferentes niveles de resolución, y que ofrezca suficiente precisión en sus resultados. La dificultad intrínseca de los fenómenos que allí ocurren, sobre todo los ligados a la interfase entre ambas fases, hace que los códigos de bajo o medio nivel de resolución, como pueden ser los códigos de sistema (RELAP, TRACE, etc.) o los basados en aproximaciones 3D TFM (Two-Fluid Model) tengan serios problemas para ofrecer resultados aceptables, a no ser que se trate de escenarios muy conocidos y se busquen resultados globales. En cambio, códigos basados en alto nivel de resolución, como los que utilizan VOF (Volume Of Fluid), requirieren de un esfuerzo computacional tan elevado que no pueden ser aplicados a sistemas complejos.
En esta tesis, mediante el uso de la librería OpenFOAM se ha creado un marco de simulación de código abierto para analizar los escenarios desde niveles de resolución de microescala a macroescala, analizando las diferentes aproximaciones, así como la información que es necesaria aportar en cada una de ellas, para el estudio del régimen de bubbly flow. En la primera parte se estudia la dinámica de burbujas individuales a un alto nivel de resolución mediante el uso del método VOF (Volume Of Fluid). Esta técnica ha permitido obtener resultados precisos como la formación de la burbuja, velocidad terminal, camino recorrido, estela producida por la burbuja e inestabilidades que produce en su camino. Pero esta aproximación resulta inviable para entornos reales con la participación de más de unas pocas decenas de burbujas. Como alternativa, se propone el uso de técnicas CFD-DEM (Discrete Element Methods) en la que se representa a las burbujas como partículas discretas. En esta tesis se ha desarrollado un nuevo solver para bubbly flow en el que se han añadido un gran número de nuevos modelos, como los necesarios para contemplar los choques entre burbujas o con las paredes, la turbulencia, la velocidad vista por las burbujas, la distribución del intercambio de momento y masas con el fluido en las diferentes celdas por cada una de las burbujas o la expansión de la fase gaseosa entre otros. Pero también se han tenido que incluir nuevos algoritmos como el necesario para inyectar de forma adecuada la fase gaseosa en el sistema. Este nuevo solver ofrece resultados con un nivel de resolución superior a los desarrollados hasta la fecha.
Siguiendo con la reducción del nivel de resolución, y por tanto los recursos computacionales necesarios, se efectúa el desarrollo de un solver tridimensional de TFM en el que se ha implementado el método QMOM (Quadrature Method Of Moments) para resolver la ecuación de balance poblacional. El solver se desarrolla con los mismos modelos de cierre que el CFD-DEM para analizar los efectos relacionados con la pérdida de información debido al promediado de las ecuaciones instantáneas de Navier-Stokes. El análisis de resultados de CFD-DEM permite determinar las discrepancias encontradas por considerar los valores promediados y el flujo homogéneo de los modelos clásicos de TFM. Por último, como aproximación de nivel de resolución más bajo, se investiga el uso uso de códigos de sistema, utilizando el código RELAP5/MOD3 para analizar el modelado del flujo en condiciones de bubbly flow. El código es modificado para reproducir correctamente el flujo bifásico en tuberías verticales, comparando el comportamiento de aproximaciones para el cálculo del término d<br>L'estudi i modelatge de fluxos bifàsics, fins i tot els més simples com bubbly flow, segueix sent un repte que comporta aproximar-se als fenòmens físics que ho regeixen des de diferents nivells de resolució espacial i temporal. L'ús de codis CFD (Computational Fluid Dynamics) com a eina de modelatge està molt estesa i resulta prometedora, però ara per ara, no existeix una única aproximació o tècnica de resolució que permeta predir la dinàmica d'aquests sistemes en els diferents nivells de resolució, i que oferisca suficient precisió en els seus resultats. Les dificultat intrínseques dels fenòmens que allí ocorren, sobre tots els lligats a la interfase entre les dues fases, fa que els codis de baix o mig nivell de resolució, com poden ser els codis de sistema (RELAP,TRACE, etc.) o els basats en aproximacions 3D TFM (Two-Fluid Model) tinguen seriosos problemes per a oferir resultats acceptables , llevat que es tracte d'escenaris molt coneguts i se persegueixen resultats globals. En canvi, codis basats en alt nivell de resolució, com els que utilitzen VOF (Volume Of Fluid), requereixen d'un esforç computacional tan elevat que no poden ser aplicats a sistemes complexos.
En aquesta tesi, mitjançant l'ús de la llibreria OpenFOAM s'ha creat un marc de simulació de codi obert per a analitzar els escenaris des de nivells de resolució de microescala a macroescala, analitzant les diferents aproximacions, així com la informació que és necessària aportar en cadascuna d'elles, per a l'estudi del règim de bubbly flow. En la primera part s'estudia la dinàmica de bambolles individuals a un alt nivell de resolució mitjançant l'ús del mètode VOF. Aquesta tècnica ha permès obtenir resultats precisos com la formació de la bambolla, velocitat terminal, camí recorregut, estela produida per la bambolla i inestabilitats que produeix en el seu camí. Però aquesta aproximació resulta inviable per a entorns reals amb la participació de més d'unes poques desenes de bambolles. Com a alternativa en aqueix cas es proposa l'ús de tècniques CFD-DEM (Discrete Element Methods) en la qual es representa a les bambolles com a partícules discretes. En aquesta tesi s'ha desenvolupat un nou solver per a bubbly flow en el qual s'han afegit un gran nombre de nous models, com els necessaris per a contemplar els xocs entre bambolles o amb les parets, la turbulència, la velocitat vista per les bambolles, la distribució de l'intercanvi de moment i masses amb el fluid en les diferents cel·les per cadascuna de les bambolles o els models d'expansió de la fase gasosa entre uns altres. Però també s'ha hagut d'incloure nous algoritmes com el necessari per a injectar de forma adequada la fase gasosa en el sistema. Aquest nou solver ofereix resultats amb un nivell de resolució superior als desenvolupat fins la data.
Seguint amb la reducció del nivell de resolució, i per tant els recursos computacionals necessaris, s'efectua el desenvolupament d'un solver tridimensional de TFM en el qual s'ha implementat el mètode QMOM (Quadrature Method Of Moments) per a resoldre l'equació de balanç poblacional. El solver es desenvolupa amb els mateixos models de tancament que el CFD-DEM per a analitzar els efectes relacionats amb la pèrdua d'informació a causa del promitjat de les equacions instantànies de Navier-Stokes. L'anàlisi de resultats de CFD-DEM permet determinar les discrepàncies ocasionades per considerar els valors promitjats i el flux homogeni dels models clàssics de TFM. Finalment, com a aproximació de nivell de resolució més baix, s'analitza l'ús de codis de sistema, utilitzant el codi RELAP5/MOD3 per a analitzar el modelatge del fluxos en règim de bubbly flow. El codi és modificat per a reproduir correctament les característiques del flux bifàsic en canonades verticals, comparant el comportament d'aproximacions per al càlcul del terme de drag basades en velocitat de drift flux model i de les basades en coe<br>Peña Monferrer, C. (2017). Computational fluid dynamics multiscale modelling of bubbly flow. A critical study and new developments on volume of fluid, discrete element and two-fluid methods [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/90493<br>TESIS
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Brandely, Anaïs. "Étude du ballottement de fluide dans les réservoirs à carburant : approches numérique et expérimentale." Thesis, Compiègne, 2016. http://www.theses.fr/2016COMP2274/document.
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L’émergence de bruits auparavant inaudibles dans les réservoirs à carburants automobiles requiert des constructeurs une meilleure compréhension des phénomènes physiques intervenants au sein de leurs produits. Dans cette thèse, différents travaux ont été conduits autour de l’étude du ballottement de fluide dans une cuve rigide rectangulaire partiellement remplie de fluide et soumise à une excitation extérieure. La première partie présente un état de l’art sur le sloshing suivant trois approches complémentaires - approche analytique, approche numérique et approche expérimentale - permettant d’orienter les travaux. Dans une deuxième partie, une étude préliminaire sur le sloshing dans une cuve rectangulaire soumise à une excitation harmonique forcée est réalisée. La confrontation des résultats numériques entre une approche linéaire - basée sur la théorie d’écoulement potentiel tenant compte de la viscosité du fluide [Schotté et Ohayon, 2013] - et une approche non linéaire commerciale – basée sur la résolution des équations de Navier-Stokes - permet de définir un paramètre de linéarité. Ce dernier permet de déterminer les cas de sloshing qui nécessitent une résolution non linéaire et ceux pour lesquels la théorie linéaire suffit pour prédire le phénomène. La troisième partie de ce document présente une étude expérimentale du ballottement de fluide dans une cuve rectangulaire rigide soumise à un freinage automobile. Deux niveaux de remplissage créant deux types d’impacts contre les parois (avec et sans enfermement de poche d’air) ont été analysés. Les essais menés ont permis de mesurer les forces engendrées par le mouvement du fluide, les pressions d’impact en paroi ainsi que le champ de vitesse par méthode Particle Image Velocimetry (PIV). Ce chapitre constitue une importante base de données expérimentales ayant permis d’étudier précisément le phénomène physique. L’étude est complétée par une confrontation des résultats expérimentaux avec des résultats Computational Fluid Dynamics (CFD). Enfin, pour conclure ce mémoire, une étude du sloshing dans un réservoir en tenant compte de la Fluid-Structure Interaction (FSI) est présentée. Le choix du couplage a été porté sur un schéma partitionné itératif faible avec, dans un premier temps, une approche potentielle instationnaire, puis avec une approche Volume Of Fluid (VOF) pour la physique fluide. Les limites d’un tel couplage dans le cas d’étude d’un réservoir partiellement rempli de fluide et attaché de manière flexible en fonction du rapport de masse fluide-réservoir ont été mises en évidence. La correction du schéma de couplage par l’effet de masse ajoutée présentée dans [Song et al., 2013] permet la résolution d’un système couplé quel que soit le rapport de masse en jeu et améliore de manière significative la convergence en réduisant également fortement le temps de calcul<br>The present thesis focuses on an investigation of the sloshing phenomenon in a partially filled fuel tank submitted to a harmonic excitation motion. In the first part, the confrontation of numerical results between a linear approach - taking into account viscosity - and a nonlinear approach based on a commercial code leads to define a parameter of linearity. This parameter allows determining cases of sloshing who require non-linear resolution and those who need a linear theory to predict the phenomenon. An experimental study of fluid sloshing in a rectangular tank submitted to an automotive braking is conducted. Tests leaded allow measuring global forces engendered by the motion of the fluid, pressure of fluid impact and velocity field by PIV. This chapter provides an important data base and helps to investigate on the physical phenomenon. This study is completed by CFD results. To conclude, a numerical model for fluid-structure interactions is presented. Limits of this segregated partitioned coupling in case of sloshing in tank flexibly attached are highlighted, depending mostly on the mass ratio between fluid and tank structure. An added-mass term is integrated to the corrected staggered scheme ensuring systematically the convergence of the coupled solution and reducing significantly the iterations required
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Kingsley, Thomas Charles. "Multidisciplinary design and optimisation of liquid containers for sloshing and impact." Diss., Pretoria : [s.n.], 2005. http://upetd.up.ac.za/thesis/available/etd-01242006-100142.
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Drumright-Clarke, Mary Ann. "Numerical simulations that characterize the effects of surfactant on droplets in shear flow." Diss., Virginia Tech, 2002. http://hdl.handle.net/10919/26895.
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Numerical simulations utilizing the code SURFER++ with the incorporation of an insoluble surfactant in the VOF scheme were conducted to characterize the effects of surfactant on a drop in shear flow. The drop is suspended in a matrix liquid. A parameter called reduction, which specifically relates to a percentage decrease in effective surface tension, is used to measure the surfactant amount on the interface. In a model system where reduction = 0.1, viscosity ratio = 1 and density ratio = 1, it was found that stable drops tend to be more elongated and less inclined to the primary flow direction than drops unexposed to surfactant. This can be explained by the location of surfactant at the interface as the drop evolves. Breaking drops also show a flattened angle, but exhibit shorter necks and faster time to break than similar drops without surfactant. As reduction increases, various physical characteristics of the drops change across Reynolds number.<br>Ph. D.
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Oomar, Muhammad Yusufali. "A Volume of Fluid (VoF) based all-mach HLLC Solver for Multi-Phase Compressible Flow with Surface-Tension." Master's thesis, Faculty of Engineering and the Built Environment, 2021. http://hdl.handle.net/11427/33935.
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This work presents an all-Mach method for two-phase inviscid flow in the presence of surface tension. A modified version of the Hartens, Lax, Leer and Contact (HLLC) approximate Riemann solver based on Garrick et al. [1] is developed and combined with the popular Volume of Fluid (VoF) method: Compressive Interface Capturing Scheme for Arbitrary Meshes (CICSAM). This novel combination yields a scheme with both HLLC shock capturing as well as accurate liquid-gas interface tracking characteristics. To ensure compatibility with VoF, the Monotone Upstream-centred Scheme for Conservation Laws (MUSCL) [2] is applied to non-conservative (primitive) variables, which yields both robustness and accuracy. Liquid-gas interface curvature is computed via both height functions [3, 4] and the convolution method [5]. This is in the interest of applicability to both cartesian and arbitrary meshes. The author emphasizes the use of VoF in the interest of surface tension modelling accuracy. The method is validated using a range of test-cases available in literature. The results show flow features that are in agreement with experimental and benchmark data. In particular, the use of the HLLC-VoF combination leads to a sharp volume fraction and energy field with improved accuracy (up to secondorder).
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Rahantamialisoa, Faniry Nadia Zazaravaka. "Complex fluid dynamical computations via the Finite Volume Method." Master's thesis, University of Cape Town, 2018. http://hdl.handle.net/11427/29860.
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Numerical simulations of the complex flows of viscoelastic fluids are investigated. The viscoelastic fluids are modelled, primarily, via the Johnson-Segalman constitutive model. Our Numerical approach is based on finite volume method, based on the Johnson-Segalman constitutive model and implemented on the OpenFOAM® platform. The Johnson-Segalman model also easily reduces to the Oldroyd-B model under certain conditions of the material parameters. Since computations using the Oldroyd-B model have been extensively documented in the literature, we take advantage of the mathematical modelling connection between the Johnson-Segalman and Oldroyd-B models to validate the accuracy of our Johnson-Segalman solver via reduction to the Oldroyd-B model. Numerical validation of our results is conducted via the most commonly used benchmark problems. The final aim of our work is to assess the viability and efficiency of our numerical solver via an investigation into the complex fluid dynamical processes associated with shear banding.
Books on the topic "Volume of Fluid (VOF) method"
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Moukalled, F., L. Mangani, and M. Darwish. The Finite Volume Method in Computational Fluid Dynamics. Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-16874-6.
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1960-, Malalasekera W., ed. An introduction to computational fluid dynamics: The finite volume method. 2nd ed. Pearson Education Ltd., 2007.
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Jr, N. C. Reis. Finite volume method to solve free surface fluid flow problems. UMIST, 1997.
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1960-, Malalasekera W., ed. An introduction to computational fluid dynamics: The finite volume method. New York, 1995.
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Center, Langley Research, ed. High order finite difference and finite volume WENO schemes and discontinuous Galerkin methods for CFD. ICASE, NASA Langley Research Center, 2001.
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Center, Lewis Research, ed. A control-volume method for analysis of unsteady thrust augmenting ejector flows. Lewis Research Center, National Aeronautics and Space Administration, 1988.
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Center, Lewis Research, ed. A control-volume method for analysis of unsteady thrust augmenting ejector flows. Lewis Research Center, National Aeronautics and Space Administration, 1988.
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Wood, William A. Comments on the diffusive behavior of two upwind schemes. National Aeronautics and Space Administration, Langley Research Center, 1998.
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Wood, William A. Comments on the diffusive behavior of two upwind schemes. National Aeronautics and Space Administration, Langley Research Center, 1998.
Find full textBook chapters on the topic "Volume of Fluid (VOF) method"
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Yuan, Zhicheng, Haowen Li, Meng Yang, Yongming Bian, and Li Chen. "Fluctuation of Near-Wall Pressure During the Cavitation Bubble Collapse." In Lecture Notes in Mechanical Engineering. Springer Nature Singapore, 2024. http://dx.doi.org/10.1007/978-981-97-1876-4_34.
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AbstractCavitation bubble collapse, which generates strong shock waves and high-velocity liquid jets, is responsible for the erosive damage to hydraulic components. In order to assess the fluctuation of near-wall pressure, in this work, an open-source package OpenFOAM is utilized for solving the Navier–Stokes equation. To track the liquid–air interface, the volume of fluid (VoF) method-based compressibleInterFoam solver is selected, and its shipped dynamic contact angle model is modified to obtain better accuracy when considering the wettability of substrates. Numerical methods are first validated by comparing with experiment, and then it is extended to study the effect of bubble diameter, pressure difference, and surface wettability on the fluctuation of near-wall pressure. Simulation results show that the initial sphere bubble goes through three stages of growth, shrinkage, and collapse near the wall. A larger bubble size leads to higher impact pressure due to the higher speed of the liquid jet. The difference in initial pressure in and out of the bubble has a great effect on the collapse behaviour. In addition, a hydrophobic surface, meaning hard liquid pining, can speed up the damping of near wall pressure. The findings in this work will be a guide to designing hydraulic components for limiting the erosive damages of cavitation bubble collapse.
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Mishra, Vivek K., Saroj K. Panda, Biswanath Sen, M. P. Maiya, and Dipti Samantaray. "VOF Simulations of Evaporation and Condensation Phenomenon Inside a Closed-Loop Thermosyphon." In Fluid Mechanics and Fluid Power, Volume 5. Springer Nature Singapore, 2024. http://dx.doi.org/10.1007/978-981-99-6074-3_5.
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Kolditz, Olaf. "Finite Volume Method." In Computational Methods in Environmental Fluid Mechanics. Springer Berlin Heidelberg, 2002. http://dx.doi.org/10.1007/978-3-662-04761-3_8.
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Maliska, Clovis R. "The Finite Volume Method." In Fundamentals of Computational Fluid Dynamics. Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-18235-8_3.
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Whitlow, Darryl, and Jean-Jacques Chattot. "A Finite Volume Least-Squares Method." In Computational Fluid Dynamics 2002. Springer Berlin Heidelberg, 2003. http://dx.doi.org/10.1007/978-3-642-59334-5_135.
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Moukalled, F., L. Mangani, and M. Darwish. "The Finite Volume Method." In The Finite Volume Method in Computational Fluid Dynamics. Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-16874-6_5.
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Majumdar, Pradip. "Finite Difference–Control Volume Method." In Computational Fluid Dynamics and Heat Transfer, 2nd ed. CRC Press, 2021. http://dx.doi.org/10.1201/9780429183003-8.
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Majumdar, Pradip. "Finite Difference–Control Volume Method." In Computational Fluid Dynamics and Heat Transfer, 2nd ed. CRC Press, 2021. http://dx.doi.org/10.1201/9780429183003-6.
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Majumdar, Pradip. "Finite Difference–Control Volume Method." In Computational Fluid Dynamics and Heat Transfer, 2nd ed. CRC Press, 2021. http://dx.doi.org/10.1201/9780429183003-7.
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Rao, J. S. "Finite Volume Method—Diffusion Problems." In Simulation Based Engineering in Fluid Flow Design. Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-46382-7_4.
Full textConference papers on the topic "Volume of Fluid (VOF) method"
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Salpingidou, Christina, and Kwok Kai So. "Applicability of Volume of Fluid Method to Two-Phase Flow Turbomachinery Application." In ASME Turbo Expo 2024: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2024. http://dx.doi.org/10.1115/gt2024-121558.
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Abstract Hydrodynamic bearings, based on lubrication oil, are commonly used in turbomachinery. The understanding and modeling of the air-oil two-phase flows in the bearing casing, piping and drain are important during the design phase. Given the limitations of the analytical methods and experiments, the use of robust and fast numerical methods, which can aid the engineers to assess various designs, is significant. In this paper, the use of VOF method for the air-oil flows for turbomachinery is reviewed. The paper first scrutinizes the use of VOF method for certain flow regimes from the perspective of the underlying VOF numerical method. Then, based on a detailed investigation using test rig observation of the bearing casing of a radial bearing of a turbocharger, the corresponding two-phase flow simulations using VOF are presented. Sensitivity studies are carried-out to understand the role of the key parameters and determine an appropriate CFD model. With the proper numerical setup, the CFD results are in good agreement with the test rig. The numerical setup is further applied to a common use case of air-oil two-phase flows of turbomachinery, namely the oil drain. The CFD model of the oil drain leads to realistic results and illustrates the applicability of the VOF method.
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Vishnoi, A. K., D. K. Chandraker, and P. K. Vijayan. "Analysis of Fluid Flow and Heat Transfer in a Falling Film Using Volume of Fluid Method." In 14th International Conference on Nuclear Engineering. ASMEDC, 2006. http://dx.doi.org/10.1115/icone14-89572.
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This paper deals with the applicability of VOF method for interface tracking with heat transfer and validation of the VOF approach using experimental data. A vertical channel flow problem in which the liquid is falling inside a vertical channel along one of the walls from the top is analysed and liquid–air interface is tracked. In the same problem analysis of heat transfer from the wall has been incorporated. This approach has a potential to predict liquid film thickness in a heated tube/subchannel which will lead to the evaluation of critical power (power corresponding to critical heat flux).
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Mathews, Hans-Christian, Hervé Morvan, Davide Peduto, Yi Wang, Colin Young, and Hans-Jörg Bauer. "Modelling of Hydraulic Seals Using an Axisymmetric Volume of Fluid Method (VOF)." In ASME Turbo Expo 2013: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/gt2013-95070.
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Hydraulic seals are used in aero engines because of their excellent sealing properties. Sealing of oil inside bearing chambers is extremely important as leakage of oil into internal spaces of the engine increases the oil consumption and can result in undesirable effects, ranging from cosmetic to mechanical. A robust dimensioning of the seal is therefore essential. However, the maximum pressure capacity of the hydraulic seal is not always determined accurately enough with many of the existing design approaches, so a high safety factor must be used. It is desirable to keep improving the accuracy of these methods, in particular to handle ever larger pressure differences. A new dimensionless design method is therefore introduced here to improve the determination of the maximum pressure capacity. This paper reports on a numerical CFD investigation using an axisymmetric Volume-of-Fluid (VOF) method building on the work of Young and Chew [1]. The numerical results are validated with the results of a two-shaft test rig, alongside analytical calculation results. Additionally, a parametric study based on CFD simulations is performed to identify dominant influence quantities. The parameters include the fluid properties of oil, the shaft speeds and the geometry parameters of the seal. Employing a data reduction approach, a new dimensionless number is introduced which allows the presentation of experimental and numerical results of the hydraulic seal in a dimensionless form. Based on this representation, a correlation is proposed, which shows a very promising trend. This validated CFD investigation and subsequent correlation introduced here show significant potential for the dimensionless description of hydraulic seals and their maximum pressure capacity.
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Quan, Shaoping, Peter Kelly Senecal, Eric Pomraning, et al. "A One-Way Coupled Volume of Fluid and Eulerian-Lagrangian Method for Simulating Sprays." In ASME 2016 Internal Combustion Engine Division Fall Technical Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/icef2016-9390.
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Volume of Fluid (VOF) and Eulerian-Lagrangian (EL)/Discrete Droplet Methods (DDM) are two of the most widely used methods in spray simulations. It is well known that these two methods have their pros and cons. VOF is good at capturing the transient detailed flow physics, while it is usually very expensive. EL is very efficient; however, to inject spray parcels, some experimental/pre-computed information is needed, such as rate of injection, and/or the parcel radius distributions, etc. It is often the case, the detailed fluid flow information at the nozzle exit, which is essential for downstream droplet breakup and coalescence, cannot be accounted in the EL method. In this paper, we developed a one-way coupled approach, in which VOF is employed to compute the detailed fluid field in the injector and this fluid information is then utilized by EL for the injection of parcels at the nozzle exit. The one-way coupled approach is used to calculate some ECN (Engine Combustion Network) spray cases, such as Spray A and Spray H. The simulated results are compared to the experimental data, and satisfactory agreement is obtained.
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Han, Jaehoon, and Ales Alajbegovic. "Simulation of Multiphase Flows in Complex Geometry Using a Hybrid Method Combining the Multi-Fluid and the Volume-of-Fluid (VOF) Approaches." In ASME 2002 Joint U.S.-European Fluids Engineering Division Conference. ASMEDC, 2002. http://dx.doi.org/10.1115/fedsm2002-31153.
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A computational method combining the multi-fluid and the Volume-of-Fluid (VOF) approaches is presented to simulate industrial multiphase flows in complex geometry. This method is particularly applicable for flows where well-defined interfaces between different phases/fluids co-exist with small-scale multiphase structures. The interfaces in relatively large scales (that can be accurately resolved on a computational mesh with a practical size) are tracked by the VOF method, whereas the small scale multiphase flow structures (that are too computationally expensive to be explicitly tracked by the VOF method) are accounted for by using the multi-fluid approach. In order to provide more computational flexibility, any two of the phases tracked by the multi-fluid approach can either have different velocities (two-fluid model) or share the same velocities (equilibrium model). The hybrid method presented here enables efficient simulation of complex flows with multiple phases/fluids on arbitrary-shaped unstructured meshes. It is fully implemented in the commercial CFD software, AVL FIRE/SWIFT. The governing equations are discretized based on a finite volume method (FVM) and the pressure field is obtained using the SIMPLE algorithm. The effect of surface tension is also included for the phases tracked by the VOF method using a Continuum Surface Force (CSF) model. Application to a well-established example of multiphase flow—a Taylor bubble rising inside a stagnant liquid—is presented to demonstrate the capability of the method.
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Chakraborty, Bhaskar, Mirko Gallo, Marco Marengo, et al. "An Enhanced Volume of Fluid Based Numerical Modelling Approach for Sub-Micron Scale Boiling Heat Transfer." In ASME 2024 7th International Conference on Micro/Nanoscale Heat and Mass Transfer. American Society of Mechanical Engineers, 2024. http://dx.doi.org/10.1115/mnhmt2024-128730.
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Abstract To explore the complicated physics of boiling heat transfer, researchers are increasingly using numerical simulation methods like the Volume of Fluid (VOF) and the Diffuse Interface (DI) approaches. The VOF method, popular for macro-scale simulations (μm to mm), effectively tracks the bubble growth and detachment. On the other hand, the DI method, which represents the interface as a continuous phase field, is mainly used for mesoscale simulations (nm to μm). The DI method is precise in resolving microscopic interfacial phenomena, but is computationally expensive for larger domains. Based on the pros and cons of the VOF and DI methods, a multi-scale modeling approach that combines the strengths of both can be utilised in the future. To pursue the goal, an initial attempt is taken to check the scaling capability of VOF in lower spatial and temporal limits. Therefore, an enhanced customised VOF methodology that has been developed within the OpenFOAM tool-box is employed here for various bubble growth scenarios exploring its applicability at progressively lower temporal and spatial scales, scaling down traditional application scales with a factor of 10 and 100, aiming to identify the resulting accuracy. It is shown for the first time, that the enhanced VOF model can accurately and effectively simulate phase-change and boiling behaviour at sub-micron scales that have not been explored in the past.
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López, J., P. Gómez, C. Zanzi, F. Faura, and J. Hernández. "Application of Non-Convex Analytic and Geometric Tools to a PLIC-VOF Method." In ASME 2016 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/imece2016-67409.
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An efficient approach to handle either convex or non-convex arbitrary polytopes is applied to volume truncation and volume conservation enforcement operations involved in volume of fluid (VOF) methods. A comparison between the proposed approach and conventional procedures based on convex decomposition is carried out for different tests, demonstrating that the proposed tools represent a substantial improvement in computational efficiency. A speedup of around one order of magnitude is achieved for the reconstruction of several interfacial shapes. The non-convex tools have been used to implement a highly accurate volume of fluid (VOF) method based on a multidimensional advection scheme with edge-matched flux polyhedra and a piecewise linear interface calculation (PLIC) method. A preliminary analysis of the accuracy, computational efficiency and volume conservation properties of the implemented PLIC-VOF method is carried out.
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Rezaeimoghaddam, Mohammad, Hossein Moin, M. R. Modarres Razavi, Mohammad Pasandideh-Fard, and Rasool Elahi. "Optimization of a High Pressure Swirl Injector by Using Volume-of-Fluid (VOF) Method." In ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2010. http://dx.doi.org/10.1115/esda2010-24614.
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In this paper, the effects of various geometric parameters of a high pressure swirl Gasoline Direct Injector (GDI) on the injection flow quality are investigated. The two-dimensional axisymmetric Navier-Stokes equations coupled with the Volume-of-Fluid (VOF) method were employed for simulation of the formation mechanism of the liquid film inside the swirl chamber and the orifice hole of the pressure swirl atomizer. To validate the model, results for base injector were compared in the steady state operation with those of available experiments in the literature. Good agreements were obtained for discharge coefficient (Cd) and cone angle (θ) with experimental data. The effects of five characteristic geometric parameters of swirl injectors such as orifice ratio (orifice length to orifice diameter), angle of swirl chamber, orifice diameter, needle lift and needle head angle (assumed to be cone) were investigated. The results show that increasing the swirl chamber angle leads to an increase in mass flow rate and a decrease of the cone angle of liquid sheet. Through extensive simulations, geometric parameters of an optimum injector were obtained.
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Chen, Y. G., W. G. Price, and P. Temarel. "An Improved Anti-Diffusive VOF Method to Predict Two-Fluid Free Surface Flows." In ASME 2011 30th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2011. http://dx.doi.org/10.1115/omae2011-50220.
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This investigation continues the development of an anti-diffusive volume of fluid method [1] by improving accuracy through the addition of an artificial diffusion term, with a negative diffusion coefficient, to the original advection equation describing the evolution of the fluid volume fraction. The advection and diffusion processes are split into a set of two partial differential equations (PDEs). The improved anti-diffusive Volume of Fluid (VOF) method is coupled with a two-fluid flow solver to predict free surface flows and illustrated by examples given in two-dimensional flows. The first numerical example is a solitary wave travelling in a tank. The second example is a plunging wave generated by flow over a submerged obstacle of prescribed shape on a horizontal floor. The computational results are validated against available experimental data.
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Liovic, Petar. "Towards 3D Volume-of-Fluid Methods Featuring Subgrid-Scale Capturing of Interface Curvature." In ASME 2014 4th Joint US-European Fluids Engineering Division Summer Meeting collocated with the ASME 2014 12th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/fedsm2014-21968.
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A new interface reconstruction method for Volume of Fluid (VOF) interface tracking is presented here, based on subgrid-scale planar interface segment reconstruction (SGS-PISR). In the SGS-PISR method implemented here, the centroid of the initial single-surface interface reconstruction is shifted along that normal to enclose the correct volume. An additional step then moves the SGS plane segments laterally outwards, to ameliorate the SGS curvature by blunting the protrusion of the centroid. The SGS-PISR method results in promising tendency towards second-order accuracy and more importantly reduced interface reconstruction errors across a range of mesh resolutions, and is targeted at improving VOF performance in resolving small grid-scale details of the interface topologies in interfacial flow CFD computations.
Reports on the topic "Volume of Fluid (VOF) method"
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Lee, Seong-Young, Jeffrey Naber, Mehdi Raessi, Roberto Torelli, Riccardo Scarcelli, and Sibendu Som. Evaporation Submodel Development for Volume of Fluid (eVOF) Method Applicable to Spray-Wall Interaction Including Film Characteristics with Validation at High Pressure and Temperature Conditions. Office of Scientific and Technical Information (OSTI), 2020. http://dx.doi.org/10.2172/1608768.
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Lee, Seong-Young, Mehdi Raessi, Roberto Torelli, Jeff Naber, Riccardo Scarcelli, and Sibendu Som. Evaporation Sub-model Development for Volume of Fluid (eVOF) Method Applicable to Spray-Wall Interaction Including Film Characteristics with Validation at High Pressure and Temperature Conditions. Office of Scientific and Technical Information (OSTI), 2016. http://dx.doi.org/10.2172/1606386.
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Delwiche, Michael, Boaz Zion, Robert BonDurant, Judith Rishpon, Ephraim Maltz, and Miriam Rosenberg. Biosensors for On-Line Measurement of Reproductive Hormones and Milk Proteins to Improve Dairy Herd Management. United States Department of Agriculture, 2001. http://dx.doi.org/10.32747/2001.7573998.bard.
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The original objectives of this research project were to: (1) develop immunoassays, photometric sensors, and electrochemical sensors for real-time measurement of progesterone and estradiol in milk, (2) develop biosensors for measurement of caseins in milk, and (3) integrate and adapt these sensor technologies to create an automated electronic sensing system for operation in dairy parlors during milking. The overall direction of research was not changed, although the work was expanded to include other milk components such as urea and lactose. A second generation biosensor for on-line measurement of bovine progesterone was designed and tested. Anti-progesterone antibody was coated on small disks of nitrocellulose membrane, which were inserted in the reaction chamber prior to testing, and a real-time assay was developed. The biosensor was designed using micropumps and valves under computer control, and assayed fluid volumes on the order of 1 ml. An automated sampler was designed to draw a test volume of milk from the long milk tube using a 4-way pinch valve. The system could execute a measurement cycle in about 10 min. Progesterone could be measured at concentrations low enough to distinguish luteal-phase from follicular-phase cows. The potential of the sensor to detect actual ovulatory events was compared with standard methods of estrus detection, including human observation and an activity monitor. The biosensor correctly identified all ovulatory events during its testperiod, but the variability at low progesterone concentrations triggered some false positives. Direct on-line measurement and intelligent interpretation of reproductive hormone profiles offers the potential for substantial improvement in reproductive management. A simple potentiometric method for measurement of milk protein was developed and tested. The method was based on the fact that proteins bind iodine. When proteins are added to a solution of the redox couple iodine/iodide (I-I2), the concentration of free iodine is changed and, as a consequence, the potential between two electrodes immersed in the solution is changed. The method worked well with analytical casein solutions and accurately measured concentrations of analytical caseins added to fresh milk. When tested with actual milk samples, the correlation between the sensor readings and the reference lab results (of both total proteins and casein content) was inferior to that of analytical casein. A number of different technologies were explored for the analysis of milk urea, and a manometric technique was selected for the final design. In the new sensor, urea in the sample was hydrolyzed to ammonium and carbonate by the enzyme urease, and subsequent shaking of the sample with citric acid in a sealed cell allowed urea to be estimated as a change in partial pressure of carbon dioxide. The pressure change in the cell was measured with a miniature piezoresistive pressure sensor, and effects of background dissolved gases and vapor pressures were corrected for by repeating the measurement of pressure developed in the sample without the addition of urease. Results were accurate in the physiological range of milk, the assay was faster than the typical milking period, and no toxic reagents were required. A sampling device was designed and built to passively draw milk from the long milk tube in the parlor. An electrochemical sensor for lactose was developed starting with a three-cascaded-enzyme sensor, evolving into two enzymes and CO2[Fe (CN)6] as a mediator, and then into a microflow injection system using poly-osmium modified screen-printed electrodes. The sensor was designed to serve multiple milking positions, using a manifold valve, a sampling valve, and two pumps. Disposable screen-printed electrodes with enzymatic membranes were used. The sensor was optimized for electrode coating components, flow rate, pH, and sample size, and the results correlated well (r2= 0.967) with known lactose concentrations.
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Styling Parameter Optimization of the Type C Recreational Vehicle Air Drag. SAE International, 2021. http://dx.doi.org/10.4271/2021-01-5094.
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Recreational vehicles have a lot of potential consumers in China, especially the type C recreational vehicle is popular among consumers due to its advantages, prompting an increase in the production and sales volumes. The type C vehicle usually has a higher air drag than the common commercial vehicles due to its unique appearance. It can be reduced by optimizing the structural parameters, thus the energy consumed by the vehicle can be decreased. The external flow field of a recreational vehicle is analyzed by establishing its computational fluid dynamic (CFD) model. The characteristic of the RV’s external flow field is identified based on the simulation result. The approximation models of the vehicle roof parameters and air drag and vehicle volume are established by the response surface method (RSM). The vehicle roof parameters are optimized by multi-objective particle swarm optimization (MO-PSO). According to the comparison, the air drag is reduced by 2.89% and the vehicle volume is increased by 0.36%. For the RV, the proper geometry parameters can increase the inner space of the vehicle while reducing the air drag.