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Littérature scientifique sur le sujet « Coupled Level Set Volume-of-Fluid (CLSVoF)) »

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Publié le 15 mars 2025

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Articles de revues sur le sujet "Coupled Level Set Volume-of-Fluid (CLSVoF))"

Shang, Zhi, Jing Lou et Hongying Li. « Simulations of Flow Transitions in a Vertical Pipe Using Coupled Level Set and VOF Method ». International Journal of Computational Methods 14, n^o 02 (22 février 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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Zhang, Guanlan, Jinqiang Gao et Chuansong Wu. « Numerical Simulation of Friction Stir Welding of Dissimilar Al/Mg Alloys Using Coupled Level Set and Volume of Fluid Method ». Materials 17, n^o 12 (19 juin 2024) : 3014. http://dx.doi.org/10.3390/ma17123014.

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The coupled level set and volume of fluid (CLSVOF) method is proposed to simulate the material distribution and physical properties during dissimilar aluminum/magnesium friction stir welding (FSW) process more accurately. Combined with a computational fluid dynamics model, the FSW process is numerically simulated and the heat transfer and material flow are analyzed. The results show that heat transfer and material flow have great influence on the Al/Mg bonding. In order to verify the accuracy of the model, the calculated results based on different methods are compared with the experimental results, and the Al/Mg interface simulated by the CLSVOF method is in better agreement with the experimental results. Finally, the material distribution and interface evolution near the tool at different times were studied based on the CLSVOF method.

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Kim, Huichan, et Sunho Park. « Coupled Level-Set and Volume of Fluid (CLSVOF) Solver for Air Lubrication Method of a Flat Plate ». Journal of Marine Science and Engineering 9, n^o 2 (22 février 2021) : 231. http://dx.doi.org/10.3390/jmse9020231.

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With the implementation of the energy efficiency design index (EEDI) by the International Maritime Organization (IMO), the goal of which is to reduce greenhouse gas (GHG) emissions, interest in energy saving devices (ESDs) is increasing. Among such ESDs are air lubrication methods, which reduce the frictional drag of ships by supplying air to the hull surface. This is one of the efficient approaches to reducing a ship’s operating costs and making it environmentally friendly. In this study, the air lubrication method on a flat plate was studied using computational fluid mechanics (CFD). OpenFOAM, the open-source CFD platform, was used. The coupled level-set and volume of fluid (CLSVOF) solver, which combines the advantages of the level-set method and the volume of fluid method, was used to accurately predict the air and water interface. Rayleigh–Taylor instability was simulated to verify the CLSVOF solver. The frictional drag reduction achieved by the air lubrication of the flat plate at various injected airflow rates was studied, and compared with experimental results. The characteristics of the air and water interface and the main factors affecting the cavity formation were also investigated.

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Qi, Fengsheng, Shuqi Zhou, Liangyu Zhang, Zhongqiu Liu, Sherman C. P. Cheung et Baokuan Li. « Numerical Study on Interfacial Structure and Mixing Characteristics in Converter Based on CLSVOF Method ». Metals 13, n^o 5 (2 mai 2023) : 880. http://dx.doi.org/10.3390/met13050880.

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The blowing flow is a key factor in molten bath stirring to affects the steel-bath interface fluctuation and chemical reaction in the top-bottom-blowing converter. The Volume of Fluid (VOF) method is widely used to capture the gas-liquid interface. However, some limitations exist in dealing with the interface curvature and normal vectors of the complex deformed slag-bath interface. The Coupled Level-Set and Volume of Fluid (CLSVOF) method uses the VOF function to achieve mass conservation and capture interface smoothly by computing the curvature and normal vector using the Level-Set function to overcome the limitations in the VOF model. In the present work, a three-dimensional (3D) transient mathematical model coupled CLSVOF method has been developed to analyze the mixing process under different injection flow rates and bottom-blowing positions. The results show that when the bottom-blowing flow rate increases from 0.252 kg/s to 0.379 kg/s, the mixing time in the molten bath gradually decreases from 74 s to 66 s. When the bottom-blowing flow rate is 0.252 kg/s, it is recommended to distribute the outer bottom-blowing position on concentric circles with Dtuy,2/D2 = 0.33.

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Suh, Young-Ho, et Gi-Hun Son. « Numerical Study of Droplet Impact on Solid Surfaces Using a Coupled Level Set and Volume-of-Fluid Method ». Transactions of the Korean Society of Mechanical Engineers B 27, n^o 6 (1 juin 2003) : 744–52. http://dx.doi.org/10.3795/ksme-b.2003.27.6.744.

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Yokoi, Kensuke, Ryo Onishi, Xiao-Long Deng et Mark Sussman. « Density-Scaled Balanced Continuum Surface Force Model with a Level Set Based Curvature Interpolation Technique ». International Journal of Computational Methods 13, n^o 04 (4 juillet 2016) : 1641004. http://dx.doi.org/10.1142/s0219876216410048.

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We examine the recently-proposed density-scaled balanced continuum surface force (CSF) model with a level set-based curvature interpolation technique. The density-scaled balanced CSF model is combined with a numerical framework which is based on the coupled level set and volume-of-fluid (CLSVOF) method, the tangent of hyperbola for interface capturing/weighted line interface calculation (THINC/WLIC) scheme, the constrained interpolation profile conservative semi-Langrangian with rational function (CIP-CSLR) and the volume/surface integrated average-based multi-moment method (VSIAM3). The present CSF model is examined for various bench mark problems such as drop–drop collisions and drop splashing. Comparisons of the present model results with experimental observations and those from the other CSF models show that the present CSF model can minimize spurious current and capture complicated fluid phenomena with minimizing floatsam.

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Xiao, Mingkun, Guang Yang, Yonghua Huang et Jingyi Wu. « Evaluation of different interface-capturing methods for cryogenic two-phase flows under microgravity ». Physics of Fluids 34, n^o 11 (novembre 2022) : 112124. http://dx.doi.org/10.1063/5.0127146.

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The distribution of the gas–liquid interface is crucial to the accurate calculation of the flow and heat transfer of in-orbit cryogenic propellants, for which the surface tension force overtakes the gravitational force. As an essential oxidant, liquid oxygen has a lower surface tension coefficient and viscosity than most room-temperature fluids, causing a greater possibility of interface instability and breakage. Conventional numerical methods have seldom been assessed in terms of cryogenic two-phase flows under microgravity, and commercial software cannot provide a consistent platform for the assessment. In this study, a unified code based on OpenFOAM has been developed for evaluating four interface-capturing methods for two-phase flows, namely, the algebraic volume of fluid (VoF), geometric VoF, coupled level set and VoF (CLSVoF), and density-scaled CLSVoF with a balanced force (CLSVoF-DSB) methods. The results indicate that the CLSVoF-DSB method is most accurate in predicting the interface motion, because it uses the level set function to represent the gas and liquid phases. The gas–liquid interface predicted by the CLSVoF-DSB method is the most stable because it adopts the scaling Heaviside function to weaken the effects of spurious currents and increases the stability. The numerical algorithm of the algebraic VoF method is the most simple, so it has the highest efficiency. The geometric VoF uses the isoface to locate the gas–liquid interface in a grid cell, so it can obtain the thinnest interface. In applications of liquid oxygen, the CLSVoF-DSB method should be used if the overall accuracy is required.

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Liu, Yong, Jia Li, Yu Tian, Xia Yu, Jian Liu et Bao-Ming Zhou. « CLSVOF Method to Study the Formation Process of Taylor Cone in Crater-Like Electrospinning of Nanofibers ». Journal of Nanomaterials 2014 (2014) : 1–12. http://dx.doi.org/10.1155/2014/635609.

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The application of two-phase computational fluid dynamics (CFD) for simulating crater-like Taylor cone formation dynamics in a viscous liquid is a challenging task. An interface coupled level set/volume-of-fluid (CLSVOF) method and the governing equations based on Navier-Stokes equations were employed to simulate the crater-like Taylor cone formation process. The computational results of the dynamics of crater-like Taylor cone slowly formed on a free liquid surface produced by a submerged nozzle in a viscous liquid were presented in this paper. Some experiments with different air pressures were carried out to evaluate the simulation results. The results from both CFD and experimental observations were compared and analyzed. The numerical results were consistent with the experimental results. Our study showed that the CLSVOF method gave convincing results, and the computational method is robust to extreme variations in interfacial topology.

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Yu, C. H., G. Z. Yang, Z. H. Gu et Y. L. Li. « Numerical investigation of multi rising bubbles using a Coupled Level Set and Volume Of Fluid (CLSVOF) method ». Applied Ocean Research 138 (septembre 2023) : 103629. http://dx.doi.org/10.1016/j.apor.2023.103629.

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Yahyaee, Ali, Amir Sajjad Bahman, Klaus Olesen et Henrik Sørensen. « Level-Set Interface Description Approach for Thermal Phase Change of Nanofluids ». Nanomaterials 12, n^o 13 (29 juin 2022) : 2228. http://dx.doi.org/10.3390/nano12132228.

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Simulations of thermally driven phase change phenomena of nanofluids are still in their infancy. Locating the gas–liquid interface location as precisely as possible is one of the primary problems in simulating such flows. The VOF method is the most applied interface description method in commercial and open-source CFD software to simulate nanofluids’ thermal phase change. Using the VOF method directs to inaccurate curvature calculation, which drives artificial flows (numerical non-physical velocities), especially in the vicinity of the gas–liquid interface. To recover accuracy in simulation results by VOF, a solver coupling VOF with the level-set interface description method can be used, in which the VOF is employed to capture the interface since it is a mass conserving method and the level-set is employed to calculate the curvature and physical quantities near the interface. We implemented the aforementioned coupled level-set and VOF (CLSVOF) method within the open-source OpenFOAM® framework and conducted a comparative analysis between CLSVOF and VOF (the default interface capturing method) to demonstrate the CLSVOF method’s advantages and disadvantages in various phase change scenarios. Using experimental mathematical correlations from the literature, we consider the effect of nanoparticles on the base fluid. Results shows that the new inferred technique provides more precise curvature calculation and greater agreement between simulated and analytical/benchmark solutions, but at the expense of processing time.

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Thèses sur le sujet "Coupled Level Set Volume-of-Fluid (CLSVoF))"

Valdez, Arnaut Héctor Gabriel. « Simulation des écoulements diphasiques en présence d'effets thermiques ». Electronic Thesis or Diss., Normandie, 2024. http://www.theses.fr/2024NORMIR38.

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Le développement d’approches numériques précises est nécessaire pour étudier les effets de gradients de tension de surface induites par des variations de température. Des études antérieures ont utilisé diverses méthodes, notamment les méthodes Smoothed Particle Hydrodynamics, Volume-of-fluid, levelset ou de front tracking. Ces approches se sont avérées bien adaptées pour traiter ces phénomènes physiques. La présente étude propose une implémentation dans ARCHER, le code interne de résolution des équations de Navier-Stokes, qui est basé sur la méthode couplant levelset et Volume-of-fluid. L’effet des variations de la tension superficielle en réponse aux gradients de température est incorporé. En outre, l’approximation de Boussinesq est introduite pour tenir compte de l’effet de flottabilité. Deux cas canoniques ont été examinés pour valider cette nouvelle implémentation. Le premier cas d’étude considère une interface plane entre deux fluides avec un gradient de température aligné avec l’interface. Il en résulte la génération d’un écoulement qui peut être décrit analytiquement pour une gamme de scenarii, puis reproduit à l’aide de la simulation numérique. Le deuxième cas porte sur une bulle sphérique ou circulaire soumise à un gradient de température. Il en résulte une migration de la phase dispersée. Une fois de plus, la solution analytique est utilisée pour valider l’approche numérique développée. Enfin, la dernière partie du manuscrit traite des instabilités d’écoulement diphasiques causés par la présence de gradients de température. Les instabilités thermo-convectives induites par les variations de la masse volumique (flottabilité) et/ou la tension superficielle (effet Marangoni) ont été investiguées en considérant les cas limites. Dans cette étude, des cellules d’instabilité et la déformation de l’interface ont pu être observées par l’approche numérique développée
The development of accurate numerical approaches is required to study flows driven by surface tension gradients induced by temperature variations. Previous studies have employed various methods, including Smoothed Particle Hydrodynamics, Volume-of-fluid, levelset, and front tracking. These approaches have been demonstrated to be adopted for treating this kind of physical phenomena. The present study proposes an implementation on ARCHER, the inhouse code solver for Navier-Stokes equations, which is based on the coupled levelset and volume-of-fluid method. The impact of fluctuations in surface tension in response to temperature gradients is incorporated. Furthermore, the Boussinesq approximation is introduced to account for the buoyancy effect. Two canonical cases were subject to examination to validate this novel implementation. The first case study considers a flat interface between two fluids with a temperature gradient aligned with the interface. This results in the generation of a flow that can be analytically described for a range of scenarii, which was then reproduced through numerical simulation. The second case considers a spherical or circular bubble subjected to a temperature gradient. This results in the migration of the dispersed phase. Once more, the analytical solution is employed to validate the developed numerical approach. Finally, the impact of temperature gradients is studied by considering the Rayleigh Bénard-Marangoni instability at two limits: when driven by buoyancy and when driven by Marangoni stress. The observation of instability cells and the deformation of the interface were also noted. Finally, the final section of the manuscript addresses two-phase flow instabilities precipitated by the presence of temperature gradients. Thermoconvective instabilities induced by variations in density (buoyancy) and/or surface tension (Marangoni effect) were examined by considering boundary cases. In this study, instability cells and interface deformation were observed using the numerical approach developed

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Shyam, Sunder *. « Dynamics of Bubbles and Drops in the Presence of an Electric Field ». Thesis, 2015. http://etd.iisc.ac.in/handle/2005/3833.

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The present thesis deals with two-phase electrohydrodynamic simulations of bubble and droplet dynamics under externally applied electric fields. We used the Coupled Level-Set and Volume-of-fluid method (CLSVOF) and two different electrohydrody-namic formulations to study the process of bubble and drop formation from orifices and needles, the interactions of two conducting drops immersed in a dielectric medium, and the oscillations of sessile drops under two different ways of applying external elec-tric field. For the process of bubble formation in dielectric liquids due to the injection of air from submerged orifices and needles, we show that a non-uniform electric field pro-duces smaller bubbles while a uniform electric field changes only the bubble shape. We further explain the reason behind the bubble volume reduction under a non-uniform electric field. We show that the distribution of the electric stresses on the bubble inter-face is such that very high electric stresses act on the bubble base due to a non-uniform electric field. This causes a premature neck formation and bubble detachment lead-ing to the formation of smaller bubbles. We also observe that the non-uniform elec-tric stresses pull the bubble interface contact line inside the needle. With oscillatory electric fields, we show that a further reduction in bubble sizes is possible, but only at certain electric field oscillation frequencies. At other frequencies, bubbles bigger than those under a constant electric field of strength equal to the amplitude of the AC electric field, are produced. We further study the bubble oscillation modes under an oscillatory electric field. We implemented a Volume-of-fluid method based charge advection scheme which is charge conservative and non-diffusive. With the help of this scheme, we were able to simulate the electrohydrodynamic interactions of conducting-dielectric fluid pairs. For two conducting drops inside a dielectric fluid, we observe that they fail to coalesce when the strength of the applied electric field is beyond a critical value. We observe that the non-coalescence between the two drops occur due to the charge transfer upon drop-drop contact. The electric forces which initially bring the two drops closer, switch direction upon charge transfer and pull the drops away from each other. The factors governing the non-coalescence are the electric conductivity of the drop’s liquid which governs the time scale of charge transfer relative to the capillary time scale and the magnitude of the electric forces relative to the capillary and the viscous forces. Similar observations are recorded for the interactions of a charged conducting drop with an interface between a dielectric fluid and a conducting fluid which is the same as the drop’s liquid. For the case of a pendant conducting drop attached to a capillary and without any influx of liquid from the capillary, we observed that the drop undergoes oscillations at lower values of electric potential when subjected to a step change in the applied electric potential. At higher values of electric potential, we observed the phenomenon of cone-jet formation which results due to the accumulation of the electric charges and thus the electric forces at the drop tip. For the formation of a pendant conducting drops from a charged capillary due to liquid injection, we observed that the drops are elongated in presence of an electric field. This happens because the free charge which appears at the drop tip is attracted towards the grounded electrode. This also leads to the formation of elongated liquid threads which connect the drop to the capillary during drop detachment. We plotted the variation of total electric charge inside the drops with respect to time and found the charge increases steeply as the drop becomes elongated and moves towards the grounded electrode. For sessile drop oscillations under an alternating electric field, two different modes of operations are studied. In the so called ‘Contact mode’ case, the droplet is placed on a dielectric coated grounded electrode and the charged needle electrode remains in direct contact with the drop as it oscillates. In the ‘Non-contact mode’ case, the drop is placed directly on the grounded electrode and electric potential is applied to a needle electrode which now remains far from the drop. We show that the drop oscillations in the contact mode are caused by concentration of electric forces near the three phase contact line where the electric charge accumulates because of the repulsion from the needle. For the non-contact mode, we observe that the electric charge is attracted by the needle towards the drop apex resulting in a concentration of the electric forces in that region. So the drop oscillates due to the electric forces acting on a region near the drop tip. We also present the variation of the total electric charge inside the drop with respect to time for the two cases studied.

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Shyam, Sunder *. « Dynamics of Bubbles and Drops in the Presence of an Electric Field ». Thesis, 2015. http://etd.iisc.ernet.in/2005/3833.

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蔡修齊. « Coupled Level Set and Volume-of-Fluid Method ». Thesis, 2008. http://ndltd.ncl.edu.tw/handle/60595371681048985862.

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碩士
國立交通大學
應用數學系所
96
In this paper we introduce level set method to solve heat equation on interface with Cartesian coordinate. Then we couple level set method and Volume-of-Fluid method to simulate two-phase flow for interface property and conserve the volume of inner area. Finally we add insoluble surfactant on the interface when simulating two-phase flows and observe the impact of surfactant on interface.

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Ningegowda, B. M. « Coupled level set and volume of fluid mehtod for numerical simulation of boiling flows ». Thesis, 2016. http://localhost:8080/iit/handle/2074/7174.

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Chapitres de livres sur le sujet "Coupled Level Set Volume-of-Fluid (CLSVoF))"

Mookherjee, Orkodip, Shantanu Pramanik et Atul Sharma. « Comparative CmFD Study on Geometric and Algebraic Coupled Level Set and Volume of Fluid Methods ». Dans Fluid Mechanics and Fluid Power, Volume 5, 3–15. Singapore : Springer Nature Singapore, 2024. http://dx.doi.org/10.1007/978-981-99-6074-3_1.

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Kwakkel, M., W. P. Breugem et B. J. Boersma. « DNS of Turbulent Bubbly Downflow with a Coupled Level-Set/Volume-of-Fluid Method ». Dans Direct and Large-Eddy Simulation IX, 647–53. Cham : Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-14448-1_81.

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Deka, H., G. Biswas et A. Dalal. « A Coupled Level Set and Volume-of-Fluid Method for Modeling Two-Phase Flows ». Dans Advances in Mechanical Engineering, 65–73. Singapore : Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-0124-1_7.

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Vu, Tai-Duy, et Sung-Goon Park. « Numerical Simulation of Two-Phase Flow Using Coupled Level-Set and Volume-of-Fluid Method ». Dans Lecture Notes in Mechanical Engineering, 253–59. Singapore : Springer Nature Singapore, 2024. http://dx.doi.org/10.1007/978-981-97-6211-8_35.

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Talebanfard, N., et B. J. Boersma. « Direct Numerical Simulation of Heat Transfer in Colliding Droplets by a Coupled Level Set and Volume of Fluid Method ». Dans Direct and Large-Eddy Simulation IX, 687–93. Cham : Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-14448-1_86.

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Actes de conférences sur le sujet "Coupled Level Set Volume-of-Fluid (CLSVoF))"

Xia, Huihuang, et Marc Kamlah. « Modelling Droplet Evaporation with an Improved Coupled Level Set and Volume of Fluid (I-Clsvof) Framework ». Dans The 8th World Congress on Mechanical, Chemical, and Material Engineering. Avestia Publishing, 2022. http://dx.doi.org/10.11159/htff22.127.

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Vaudor, Geoffroy, Alain Berlemont, Thibaut Ménard et Mathieu Doring. « A Consistent Mass and Momentum Flux Computation Method Using Rudman-Type Technique With a CLSVOF Solver ». Dans 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/fedsm2014-21802.

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In this paper, a computational method is presented that addresses the problem of multiphase flow characterized by phases with significant density ratio accompanied by strong shearing. The Coupled Level-Set Volume-of-Fluid (CLSVOF) technique is used for interface tracking, while the momentum transfer is coupled to that of mass by means of momentum fluxes computed using a sub-grid. This is an extended adaptation of Rudman’s volume tracking technique [1]. The new method is shown to conserve kinetic energy when applied to cases otherwise unfeasible, such as shear layer with high density ratio.

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Ray, Bahni, Gautam Biswas et Ashutosh Sharma. « Vortex Ring Formation on Drop Coalescence With Underlying Liquid ». Dans ASME 2013 Heat Transfer Summer Conference collocated with the ASME 2013 7th International Conference on Energy Sustainability and the ASME 2013 11th International Conference on Fuel Cell Science, Engineering and Technology. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/ht2013-17711.

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Numerical simulations using coupled level-set and volume-of-fluid (CLSVOF) method has been carried out to capture the vortex ring when a drop coalesces on a pool of liquid. A study has been done for the formation and motion of vortex rings generated when drops of liquid are allowed to come into contact at zero velocity with a quiescent flat surface of the same liquid.

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Deka, Hiranya, Gautam Biswas et Amaresh Dalal. « Formation and Penetration of Vortex Ring on Drop Coalescence ». Dans ASME 2016 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/imece2016-66786.

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Numerical simulations are performed using coupled level-set and volume of fluid (CLSVOF) method to capture the formation and propagation of a vortex ring when a drop coalesces at the interface of a pool of same liquid and a lighter liquid resting above it. A Vortex ring is generated near the interface on coalescence of a drop. Subsequently the vortex ring propagates into the liquid pool. The propagation of a vortex ring and its dependence on the shape as well as impact velocity of the drop are investigated in this work.

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Haghshenas, Majid, et Ranganathan Kumar. « Curvature Estimation Modeling Using Machine Learning for CLSVOF Method : Comparison With Conventional Methods ». Dans ASME-JSME-KSME 2019 8th Joint Fluids Engineering Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/ajkfluids2019-5415.

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Abstract Despite extensive progress in recent decades, curvature estimation in two-phase models remains a challenge. Well-established curvature computing techniques such as distance function, smoothed volume fraction and height-function directly estimate the interface curvature from the implicit representation of the interface. Most recently, machine learning approach has been incorporated in computational physics simulation. Machine learning is a set of algorithms that can be utilized for training a system which allows predicting the output in the future. In this work, we train a curvature estimation model using machine learning approach for Coupled Level Set Volume of Fluid (CLSVOF) method in which both distance function and volume fraction implicitly represent the interface. Three datasets for the curvature are generated: a) curvature as a function of volume fraction (nine inputs), b) curvature as a function of distance function (nine inputs), and c) curvature as a function of both volume fraction and distance function (eighteen inputs). For each interfacial cell, curvature and input parameters (nine volume fraction and nine distance function values) at nine grid points across the interface are stored. Datasets are utilized to train different curvature computing models using neural network (NN) learning algorithm. Comparison of different datasets reveals that the distance function dataset is the best input for curvature function training. Different available learning algorithms on built-in NN toolbox in Matlab are examined. The curvature estimation function is examined for a dimensional 2D well-defined droplet on different grid resolution. In addition, the curvature estimation model by machine learning approach is compared with conventional methods such as the level set method and height function method for couple of cases. First, the case of elliptical droplet is used to evaluate curvature estimation of different methods in comparison with the analytical solution. Then, the standard case of equilibrium droplet is simulated by CLSVOF solver using different curvature estimation methods to evaluate parasitic currents generation and droplet pressure prediction. The results show that the machine learning curvature function outperforms conventional methods even on coarse grids. Finally, the curvature estimation methods are is utilized to solve a practical case of rising bubble. We observed that the terminal velocity of capped bubble reported by curvature function simulation has the lowest error.

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Tong, Albert Y., et Zhaoyuan Wang. « A Numerical Method for Capillarity-Driven Free Surface Flows ». Dans ASME 2005 Fluids Engineering Division Summer Meeting. ASMEDC, 2005. http://dx.doi.org/10.1115/fedsm2005-77274.

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The continuum surface force (CSF) method has been extensively employed in the volume-of-fluid (VOF), level set (LS) and front tracking methods to model surface tension force. It is a robust method requiring relatively easy implementation. However, it is known to generate spurious currents near the interface that may lead to disastrous interface instabilities and failures of grid convergence. A different surface tension implementation algorithm, referred to as the pressure boundary method (PBM), is introduced in this study. The surface tension force is incorporated into the Navier-Stokes equation via a capillary pressure gradient while the free surface is tracked by a coupled level set and volume-of-fluid (CLSVOF) method. It has been shown that the spurious currents are greatly reduced by the present method with the sharp pressure boundary condition preserved. The numerical results of several cases have been compared with data reported in the literature and are found to be in a close agreement.

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Guan, Yin, et Albert Y. Tong. « Numerical Modeling of Droplet Splitting and Merging in a Parallel-Plate Electrowetting-on-Dielectric (EWOD) Device ». Dans ASME 2013 4th International Conference on Micro/Nanoscale Heat and Mass Transfer. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/mnhmt2013-22152.

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Micro water droplet splitting and merging in a parallel-plate electrowetting-on-dielectric (EWOD) device has been studied numerically. The transient governing equations for the microfluidic flow are solved by a finite volume scheme with a two-step projection method on a fixed computational domain. The interface between liquid and gas is tracked by a coupled Level Set and Volume-of-Fluid (CLSVOF) method. A Continuum Surface Force (CSF) model is employed to model the surface tension at the interface. The physics of the fluid dynamics within the EWOD device has been examined. Contact angle hysteresis, which is an essential component in EWOD, is implemented together with a simplified model for the viscous stresses exerted by the two plates at the solid-liquid interface. The results of the numerical model have been validated with published experimental data. A parametric study has been performed in which the effects of channel height and several other parameters on the fluid motion have been studied.

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Wang, Zhaoyuan, et Albert Y. Tong. « A Sharp Surface Tension Modeling Method for Capillarity-Dominant Two-Phase Incompressible Flows ». Dans ASME 2007 International Mechanical Engineering Congress and Exposition. ASMEDC, 2007. http://dx.doi.org/10.1115/imece2007-42455.

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A surface tension implementation algorithm for two-phase incompressible interfacial flows is presented in this study. The surface tension effect is treated as a jump condition at the interface and incorporated into the Navier-Stokes equation via a capillary pressure gradient. The interface is tracked by a coupled level set and volume-of-fluid (CLSVOF) method based on the finite-volume formulation on a fixed Eulerian grid. It has been shown in a stationary benchmark test the spurious currents are greatly reduced and the sharp pressure jump across the interface is well preserved. Numerical instabilities caused by the sharp treatment on a fixed grid are avoided. Several dynamic tests are performed to further validate the accuracy and versatility of the present method, the results of which are in good agreement with data reported in the literature.

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Tarlet, Dominique, Philippe Desjonquères, Thibault Ménard et Jérôme Bellettre. « Comparison between numerical and experimental water-in-oil dispersion in a microchannel ». Dans ILASS2017 - 28th European Conference on Liquid Atomization and Spray Systems. Valencia : Universitat Politècnica València, 2017. http://dx.doi.org/10.4995/ilass2017.2017.4717.

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The dispersion of water inside a flow of oil is investigated in a microfluidic device, producing a water-in-oilemulsion. The liquid–liquid flow mainly differs from those presented in existing literature through its high capillary number (between 3 and 14), and in the head-on collision between water and oil streams. By comparing with experimental data, numerical simulations can provide more information about the topology of the flow. A coupled Volume of Fluid and Level Set method (CLSVOF) is used to treat the interface between both phases and incompressible Navier-Stokes equations are solved. Three set of parameters, close to those in the experimental setup, are investigated to compare experimental and numerical results. The comparison between experiments and simulation provides a precise knowledge of the liquid-liquid dispersion process and the overall flow patternwithin the microfluidic device.DOI: http://dx.doi.org/10.4995/ILASS2017.2017.4717

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Wang, Zhaoyuan, et Albert Y. Tong. « Deformation and Oscillations of a Single Gas Bubble Rising in a Narrow Vertical Tube ». Dans ASME 4th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2006. http://dx.doi.org/10.1115/icnmm2006-96246.

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A single gas bubble rising in a narrow vertical tube is investigated via a numerical model on a 3-D axisymmetric computational domain. The transient governing equations are solved by a finite volume scheme with a two-step projection method. The interface between the liquid and gas phase is tracked by a coupled level set and volume-of-fluid (CLSVOF) method. A surface tension modeling method, which preserves the jump discontinuity of pressure at the interface, is employed. The flow structure and terminal velocity obtained in the numerical simulation are in excellent agreement with experimental measurements. Special attention is paid to the bubble oscillations during the initial stage of ascent. It has been found that the bubble bottom undergoes severe oscillations while the nose maintains a stable shape. A parametric study is performed to identify the factors controlling the oscillations at the bubble bottom.

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