Articles de revues : « Coupled Level Set Volume-of-Fluid (CLSVoF)) »

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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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Dewangan, Satish Kumar, Santosh Kumar Senapati et Vivek Deshmukh. « CFD Investigation of Parameters Affecting Oil-Water Stratified Flow in a Channel ». International Journal of Mathematical, Engineering and Management Sciences 5, n^o 4 (1 août 2020) : 602–13. http://dx.doi.org/10.33889/ijmems.2020.5.4.049.

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Stratified flow is a common occurrence for various internal flow based industrial multiphase flow patterns. This involves fully or partially well-defined interface which continuously evolve with space and time. Hence stratified flow analysis essentially involves proper interface capturing approach. The present work focuses on the numerical analysis of oil-water stratified pattern using the Coupled level set and volume of fluid method (CLSVOF) in ANSYS Fluent in a two-dimensional channel. The work involves predicting the effect of density ratio, kinematic viscosity and surface tension coefficient on the mixture velocity and total pressure changes. At outset, the final conclusions may be gainfully employed in oil transportation pipeline, chemical industries and in pipeline flow control administration, etc.

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Yang, Shanshan, Quanyuan Zeng, Xiaohua Zhang, Chunzhu Dong et Ling Guan. « Numerical Simulation of Single Droplet Impingement upon Dynamic Liquid Film Obliquely ». Mathematics 10, n^o 17 (4 septembre 2022) : 3193. http://dx.doi.org/10.3390/math10173193.

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To better understand the application of droplet impingement in industry and agriculture, in this paper, the coupled level set and volume of fluid (CLSVOF) method is applied to study droplet oblique impact on a dynamic liquid film. The conclusions are the following: the downstream crown height increases and then decreases as the impact angle increases, whereas upstream crown height and spreading length decrease significantly; moreover, the spreading length and upstream crown height increase with the increase of film velocity, while the downstream crown height decreases instead. The increase of gas density inhibits both upstream and downstream crowns. When the fluid viscosity decreases or the impact velocity increases, the crown height increases significantly, which easily leads to crown rupture or droplet splash. The increase in impact velocity leads to an increase in spreading length; however, viscosity has almost no effect on the spreading length.

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Ray, B., G. Biswas et A. Sharma. « Oblique Drop Impact on Deep and Shallow Liquid ». Communications in Computational Physics 11, n^o 4 (avril 2012) : 1386–96. http://dx.doi.org/10.4208/cicp.140510.150511s.

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AbstractNumerical simulations using CLSVOF (coupled level set and volume of fluid) method are performed to investigate the coalescence and splashing regimes when a spherical water drop hits on the water surface with an impingement angle. Impingement angle is the angle between the velocity vector of primary drop and the normal vector to water surface. The effect of impingement angle, impact velocity and the height of target liquid are carried out. The impingement angle is varied from 0° to 90° showing the gradual change in phenomena. The formation of ship pro like shape, liquid sheet, secondary drops and crater are seen. Crater height, crater displacement, crown height and crown angle are calculated and the change in the parameters with change in impingement angle is noted.

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Wang, Xiaopeng, Shifu Zhu, Song Chen, Ning Ma et Zhe Zhang. « Proper Orthogonal Decomposition Analysis and Dispersion Characteristics of Resonant Acoustic Flow ». Shock and Vibration 2020 (4 mars 2020) : 1–13. http://dx.doi.org/10.1155/2020/5068042.

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The investigation on the flow field and mixing characteristics of resonant sound mixing is of great significance for the dispersion mixing of superfine materials. In order to simulate the flow field and dispersion characteristics of resonant acoustic mixing, a gas-liquid-solid three-phase flow model based on the coupled level-set and volume-of-fluid (CLSVOF) and discrete particle model (DPM) was established. The CLSVOF model solves the gas-liquid interface, and the DPM model tracks the particle position. Then, the particle image velocimetry (PIV) experiment was performed using a self-made resonance acoustic hybrid prototype under different oscillation accelerations, and the radial velocity distribution between the experiment and simulation was compared. Finally, the proper orthogonal decomposition (POD) is used to decompose the flow field under different oscillation accelerations and fill levels, and the energy distribution law and the energy structure of different scales are extracted. The results show that the energy of the instantaneous flow field of the resonant sound is mainly concentrated in the low-order mode, and a close relationship was revealed between the energy distribution law and dispersion behavior of particles. The larger the small-scale coherent structures distribute, the more energy it has and the more favorable it is for fast and uniform dispersion.

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Jingyu, Zhao, Lyv Yaguo, Liu Zhenxia et Ren Guozhe. « Numerical Study on the Improvement of Oil Return Structure in Aero-Engine Bearing Chambers ». International Journal of Turbo & ; Jet-Engines 35, n^o 1 (26 mars 2018) : 59–69. http://dx.doi.org/10.1515/tjj-2016-0022.

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AbstractNumerical study has been carried out to improve the unreasonable oil film accumulation and oil return effect of the bearing chamber. Ramp sump and eccentricity sump offtake structures are designed and improved, and oil-gas two-phase flow calculation model based on CLSVOF (coupled level set and volume of fluid) method is proposed. Based on the grid-independent analysis and verifying the rationality of numerical data, oil-gas movement mechanism and oil return characteristics for different scavenge offtakes are calculated and analyzed. Results show that both the ramp sump and eccentricity sump offtake structures have favorable effects on improving the local oil distribution such as recirculation and stripping, etc. at low rotation speeds and alleviating the rapid decline of scavenge efficiency at high rotation speeds. Meanwhile, the air shear force is the main reason for the rapid decline of scavenge efficiency, while the design of oil return sump makes for the oil discharge from the scavenge offtake, and the deeper the sump depth is, the better.

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Wang, Kaimin, Han Chen, Jiawei Liu, Hongyu Ge, Hongsheng Liu et Xiaohua Liu. « Effect of Eccentric Distance on Successive Dual-droplet Impacting a Super-hydrophobic Tube ». E3S Web of Conferences 299 (2021) : 01002. http://dx.doi.org/10.1051/e3sconf/202129901002.

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Droplet impact is a common but significant phenomenon in industry. The CLSVOF (coupled level set and volume-of-fluid) method is used to numerically study the successive dual-droplet impacting a super-hydrophobic tube. For the impact velocity of 1.0 m/s, the effect of the eccentric distance on dynamic characteristics is analysed, the corresponding eccentric distances are 0.5, 1.0 and 2.0, respectively. In addition, the break-up during rebound is analysed with velocity field and pressure nephogram. Results show that, the eccentric distance hinders the spread during the initial period of spreading. With the increase in eccentric distance, more liquid gathers at the eccentric side and the liquid film might rebound easily without break-up under the same impact velocity. The break-up during rebound mainly depends on the local airflow and pressure difference. The high-pressure zone near the solid-liquid interface moves towards the eccentric side with the increase in eccentric distance.

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Chu, Guidong, Lijuan Qian, Xiaokai Zhong, Chenlin Zhu et Zhongli Chen. « A Numerical Investigation on Droplet Bag Breakup Behavior of Polymer Solution ». Polymers 12, n^o 10 (23 septembre 2020) : 2172. http://dx.doi.org/10.3390/polym12102172.

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The deformation and breakup of a polymer solution droplet plays a key role in inkjet printing technology, tablet-coating process, and other spray processes. In this study, the bag breakup behavior of the polymer droplet is investigated numerically. The simple coupled level set and volume of fluid (S-CLSVOF) method and the adaptive mesh refinement (AMR) technique are employed in the droplet breakup cases at different Weber numbers and Ohnesorge numbers. The nature of the polymer solution is handled using Herschel–Bulkley constitutive equations to describe the shear-thinning behavior. Breakup processes, external flow fields, deformation characteristics, energy evolutions, and drag coefficients are analyzed in detail. For the bag breakup of polymer droplets, the liquid bag will form an obvious reticular structure, which is very different from the breakup of a Newtonian fluid. It is found that when the aerodynamic force is dominant, the increase of the droplet viscous force will prolong the breakup time, but has little effect on the final kinetic energy of the droplet. Moreover, considering the large deformation of the droplet in the gas flow, a new formula with the cross-diameter (Dcro) is introduced to modify the droplet drag coefficient.

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Zhou, Donglong, Jianlong Chang et Huawei Shan. « Investigations of the Atomization Characteristics and Mechanisms of Liquid Jets in Supersonic Crossflow ». Aerospace 10, n^o 12 (27 novembre 2023) : 995. http://dx.doi.org/10.3390/aerospace10120995.

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In the combustion chamber of scramjets, fuel jets interact with supersonic airflow in the form of a liquid jet in crossflow (LJIC). It is difficult to achieve adequate jet–crossflow mixing and the efficient combustion of fuel in an instant. Large eddy simulation (LES), the coupled level-set and volume of fluid (CLSVOF) method, and an adaptive mesh refinement (AMR) framework are used to simulate supersonic LJICs in this article. This way, LJIC atomization characteristics and mechanisms can be further explored and analyzed in detail. It is found that the surface waves of the liquid column exist in a two-dimensional form, including vertical and spanwise directions. Column breakup occurs when all the spanwise surface waves between adjacent vertical surface waves break up. Bow shock waves, composed of multiple connected arcuate shock waves, are dynamic and will change with the evolution of the liquid column. The vortex ring movement of supersonic LJICs, whose trends in the vertical and spanwise directions are different, is relatively complex, which is due to the complex and time-dependent shape of liquid columns.

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Mudawar, Issam, Sunjae Kim et Jeongmin Lee. « A coupled level-set and volume-of-fluid (CLSVOF) method for prediction of microgravity flow boiling with low inlet subcooling on the international space station ». International Journal of Heat and Mass Transfer 217 (décembre 2023) : 124644. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2023.124644.

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Ohta, Mitsuhiro, Yu Akama, Yutaka Yoshida et Mark Sussman. « Influence of the viscosity ratio on drop dynamics and breakup for a drop rising in an immiscible low-viscosity liquid ». Journal of Fluid Mechanics 752 (4 juillet 2014) : 383–409. http://dx.doi.org/10.1017/jfm.2014.339.

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AbstractIn a low Morton number ($\def \xmlpi #1{}\def \mathsfbi #1{\boldsymbol {\mathsf {#1}}}\let \le =\leqslant \let \leq =\leqslant \let \ge =\geqslant \let \geq =\geqslant \def \Pr {\mathit {Pr}}\def \Fr {\mathit {Fr}}\def \Rey {\mathit {Re}}M$) regime, the stability of a single drop rising in an immiscible viscous liquid is experimentally and computationally examined for varying viscosity ratio $\eta $ (the viscosity of the drop divided by that of the suspending fluid) and varying Eötvös number ($\mathit{Eo}$). Three-dimensional computations, rather than three-dimensional axisymmetric computations, are necessary since non-axisymmetric unstable drop behaviour is studied. The computations are performed using the sharp-interface coupled level-set and volume-of-fluid (CLSVOF) method in order to capture the deforming drop boundary. In the lower $\eta $ regimes, $\eta = 0.02 $ or 0.1, and when $\mathit{Eo}$ exceeds a critical threshold, it is observed that a rising drop exhibits nonlinear lateral/tilting motion. In the higher $\eta $ regimes, $\eta = 0.1$, 1.94, 10 or 100, and when $\mathit{Eo}$ exceeds another critical threshold, it is found that a rising drop becomes unstable and breaks up into multiple drops. The type of breakup, either ‘dumbbell’, ‘intermediate’ or ‘toroidal’, depends intimately on $\eta $ and $\mathit{Eo}$.

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Bao, Heyun, Xiaonan Hou et Fengxia Lu. « Analysis of Oil-Air Two-Phase Flow Characteristics inside a Ball Bearing with Under-Race Lubrication ». Processes 8, n^o 10 (1 octobre 2020) : 1223. http://dx.doi.org/10.3390/pr8101223.

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Under-race lubrication can increase the amount of lubricating oil entering a bearing and greatly improve lubrication and cooling effects. The oil-air two-phase flow characteristics inside a ball bearing with under-race lubrication play a key role in lubrication and cooling performance. The motions of ball bearing subassemblies are complicated. Ball spin affects the oil volume fraction. In this paper, the coupled level set volume of fluid (CLSVOF) method is used to track the oil-air two-phase flow inside the ball bearing with under-race lubrication. The influence of various factors on the oil volume fraction inside the ball bearing with under-race lubrication is investigated, particularly rotating speeds, inlet velocity and the size of oil supply apertures under the inner ring. The influence of the ball spinning is analyzed separately. The result demonstrates that, on account of the centrifugal force, lubricating oil is located more on the outer ring raceway at rotational speeds of 5000 r/min, 10,000 r/min, 15,000 r/min and 20,000 r/min. The oil volume fraction inside the bearing gradually increases at an oil inlet velocity of 5 m/s, 10 m/s and 15 m/s. The circumferential distribution of oil is also similar. As the diameter of the oil supply aperture increases from 1.5 mm to 2 mm, the oil volume fraction increases inside the ball bearing. However, the oil volume fraction slightly decreases from 2 mm to 2.5 mm of oil supply aperture diameter. Ball spin does not affect the circumferential distribution trend of the lubricating oil, but slightly reduces the oil volume fraction. Furthermore, ball spin causes the surface fluid to rotate around its rotation axis and increases the speed.

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Qian, Lijuan, Hongchuan Cong et Chenlin Zhu. « A Numerical Investigation on the Collision Behavior of Polymer Droplets ». Polymers 12, n^o 2 (24 janvier 2020) : 263. http://dx.doi.org/10.3390/polym12020263.

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Binary droplet collisions are a key mechanism in powder coatings production, as well as in spray combustion, ink-jet printing, and other spray processes. The collision behavior of the droplets using Newtonian and polymer liquids is studied numerically by the coupled level-set and volume of fluid (CLSVOF) method and adaptive mesh refinement (AMR). The deformation process, the internal flow fields, and the energy evolution of the droplets are discussed in detail. For binary polymer droplet collisions, compared with the Newtonian liquid, the maximum deformation is promoted. Due to the increased viscous dissipation, the colliding droplets coalesce more slowly. The stagnant flow region in the velocity field increases and the flow re-direction phenomenon is suppressed, so the polymer droplets coalesce permanently. As the surface tension of the polymer droplets decreases, the kinetic and the dissipated energy increases. The maximum deformation is promoted, and the coalescence speed of the droplets slows down. During the collision process, the dominant pressure inside the polymer droplets varies from positive pressure to negative pressure and then to positive pressure. At low surface tension, due to the non-synchronization in the movement of the interface front, the pressure is not smooth and distributes asymmetrically near the center of the droplets.

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Du, Yonglong, Xin Liu, Songzhe Xu, Enxiang Fan, Lixiao Zhao, Chaoyue Chen et Zhongming Ren. « Numerical Simulation of Gas Atomization and Powder Flowability for Metallic Additive Manufacturing ». Metals 14, n^o 10 (2 octobre 2024) : 1124. http://dx.doi.org/10.3390/met14101124.

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The quality of metal powder is essential in additive manufacturing (AM). The defects and mechanical properties of alloy parts manufactured through AM are significantly influenced by the particle size, sphericity, and flowability of the metal powder. Gas atomization (GA) technology is a widely used method for producing metal powders due to its high efficiency and cost-effectiveness. In this work, a multi-phase numerical model is developed to compute the alloy liquid breaking in the GA process by capturing the gas–liquid interface using the Coupled Level Set and Volume-of-Fluid (CLSVOF) method and the realizable k-ε turbulence model. A GA experiment is carried out, and a statistical comparison between the particle-size distributions obtained from the simulation and GA experiment shows that the relative errors of the cumulative frequency for the particle sizes sampled in two regions of the GA chamber are 5.28% and 5.39%, respectively. The mechanism of powder formation is discussed based on the numerical results. In addition, a discrete element model (DEM) is developed to compute the powder flowability by simulating a Hall flow experiment using the particle-size distribution obtained from the GA experiment. The relative error of the time that finishes the Hall flow in the simulation and experiment is obtained to be 1.9%.

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Han, Fangwei, Jian Li, Yingying Peng et Yue Zhao. « Exploration of the Relationships between the Spraying Condition and Wetting Behavior on Coal Surface of Dust Suppression Droplet : Improving the Utilization Rate ». Geofluids 2022 (21 décembre 2022) : 1–13. http://dx.doi.org/10.1155/2022/3464456.

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Dust suppression through water-based media is an important technical means, which is of great significance to industrial process safety and environmental protection. In order to improve the utilization rate of droplets, the dynamic spreading process of droplets impacting the coal surface was studied by the coupled level-set and volume-of-fluid methods (CLSVOF) method. The spread area was calculated by the binary method to characterize the wetting effect. Dimensionless spread area per unit volume (DSAPUV) was proposed to represent the utilization of droplets. The results show that the droplet spreading fracture process can be divided into three stages: initial deformation period, spreading fracture period, and stable period. When the particle size was not being changed, the area of dimensionless spread does not increase consistently with velocities, but there exists an optimal critical velocity of impingement, which is 17 m/s for the maximum dimensionless spread area reached by droplets with a diameter of 30 μm and 19 m/s for the maximum dimensionless spread area reached by droplets with a diameter of 50 μm. Droplet size is directly proportional to the dimensionless spread area. The maximum dimensionless spread areas of the droplets were all reached during spreading, and the time required increased gradually with increasing particle sizes. It was found that the effect of droplet size on the utilization of droplets was obvious when their size ranged from 10 μm to 50 μm, and their velocity ranged from 15 m/s to 20 m/s.

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RAY, B., G. BISWAS et A. SHARMA. « Generation of secondary droplets in coalescence of a drop at a liquid–liquid interface ». Journal of Fluid Mechanics 655 (12 mai 2010) : 72–104. http://dx.doi.org/10.1017/s0022112010000662.

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When a droplet of liquid 1 falls through liquid 2 to eventually hit the liquid 2–liquid 1 interface, its initial impact on the interface can produce daughter droplets of liquid 1. In some cases, a partial coalescence cascade governed by self-similar capillary-inertial dynamics is observed, where the fall of the secondary droplets in turn continues to produce further daughter droplets. Results show that inertia and interfacial surface tension forces largely govern the process of partial coalescence. The partial coalescence is suppressed by the viscous force when Ohnesorge number is below a critical value and also by gravity force when Bond number exceeds a critical value. Generation of secondary drop is observed for systems of lower Ohnesorge number for liquid 1, lower and intermediate Ohnesorge number for liquid 2 and for low and intermediate values of Bond number. Whenever the horizontal momentum in the liquid column is more than the vertical momentum, secondary drop is formed. A transition regime from partial to complete coalescence is obtained when the neck radius oscillates twice. In this regime, the main body of the column can be fitted to power-law scaling model within a specific time range. We investigated the conditions and the outcome of these coalescence events based on numerical simulations using a coupled level set and volume of fluid method (CLSVOF).

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Kim, Huichan, et Sunho Park. « Correction : Kim, H. ; Park, S. Coupled Level-Set and Volume of Fluid (CLSVOF) Solver for Air Lubrication Method of a Flat Plate. J. Mar. Sci. Eng. 2021, 9, 231 ». Journal of Marine Science and Engineering 10, n^o 1 (29 décembre 2021) : 29. http://dx.doi.org/10.3390/jmse10010029.

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Qian, Lijuan, Jingqi Liu, Hongchuan Cong, Fang Zhou et Fubing Bao. « A Numerical Investigation on the Collision Behavior of Unequal-Sized Micro-Nano Droplets ». Nanomaterials 10, n^o 9 (3 septembre 2020) : 1746. http://dx.doi.org/10.3390/nano10091746.

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Micro-nano droplet collisions are fundamental phenomena in the applications of nanocoating, nano spray, and microfluidics. Detailed investigations of the process of the droplet collisions under higher Weber are still lacking when compared with previous research studies under a low Weber number below 120. Collision dynamics of unequal-sized micro-nano droplets are simulated by a coupled level-set and volume of fluid (CLSVOF) method with adaptive mesh refinement (AMR). The effects of the size ratio (from 0.25 to 0.75) and different initial collision velocities on the head-on collision process of two unequal-sized droplets at We = 210 are studied. Complex droplets will form the filament structure and break up with satellite droplets under higher Weber. The filament structure is easier to disengage from the complex droplet as the size ratio increases. The surface energy converting from kinetic energy increases with the size ratio, which promotes a better spreading effect. When two droplets keep the constant relative velocity, the motion tendency of the droplets after the collision is mainly dominated by the large droplet. On one hand, compared with binary equal-sized droplet collisions, a hole-like structure can be observed more clearly since the initial velocity of a large droplet decreases in the deformation process of binary unequal-sized droplets. On the other hand, the rim spreads outward as the initial velocity of the larger droplet increases, which leads to its thickening.

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Hua, Lin, Hong Li et Yue Jiang. « Axis-Switching Behavior of Liquid Jets Issued from Non-Circular Nozzles Under Low-Intermediate Pressure ». Applied Engineering in Agriculture 37, n^o 2 (2021) : 367–78. http://dx.doi.org/10.13031/aea.14245.

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HighlightsThe flow behavior of water jets discharged from different orifices was investigated.High-speed photography (HSP) was used to obtain surface structures and spread characteristics of water jets.The deformation process in axis switching related to the corner vortices effect of non-circular jets was researched by numerical simulation.The axis switching of non-circular jets enhances entrainment ability of the jet.ABSTRACT. Low-intermediate pressure sprinkler irrigation systems are important research topics in the field of water-saving irrigation. Non-circular nozzles improve spray uniformity at lower pressures and are key components of sprinkler irrigation systems. In this article, the behavior of discharged water jets from nozzles with circular, square, and equilateral triangular orifices designed with the same flow rate was investigated. High-speed photography (HSP) was used to capture jet characteristics in the near field (z<20D). The largest spread angle was obtained for the square jet, which was on average 37% larger than that of the circular jet. In addition, numerical simulations were performed to analyze the axis-switching process using the large-eddy simulation (LES) method and the coupled level-set and volume of fluid (CLSVOF) method. The axis-switching phenomenon was observed in non-circular jets, in which surrounding air mixed with the jet and promoted the formation of thin diaphragm structures. The deformation process that occurs in axis switching is described according to the simulated vorticity and velocity fields. The research results suggest the axis-switching phenomenon is induced by corner vortex motions produced by the polygonal orifice, which accelerate the decay of the axial velocity and increase the jet entrainment rate. Thus, the effect of corner vortices should be considered in the design of polygonal nozzles. Keywords: Axis switching, High-speed photography, Liquid jet, Low-intermediate pressure sprinkler irrigation, Non-circular nozzle, Numerical simulation.

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Arienti, M., X. Li, M. C. Soteriou, C. A. Eckett, M. Sussman et R. J. Jensen. « Coupled Level-Set/Volume-of-Fluid Method for Simulation of Injector Atomization ». Journal of Propulsion and Power 29, n^o 1 (janvier 2013) : 147–57. http://dx.doi.org/10.2514/1.b34198.

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Baniabedalruhman, Ahmad. « A coupled volume-of-fluid and level set method in interDyMFoam solver ». Vibroengineering PROCEDIA 30 (2 avril 2020) : 210–13. http://dx.doi.org/10.21595/vp.2020.21342.

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Tsui, Yeng-Yung, Cheng-Yen Liu et Shi-Wen Lin. « Coupled level-set and volume-of-fluid method for two-phase flow calculations ». Numerical Heat Transfer, Part B : Fundamentals 71, n^o 2 (février 2017) : 173–85. http://dx.doi.org/10.1080/10407790.2016.1265311.

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Cui, Liying, Yingge Yang et Cuiping Ren. « Application of CVOFLS method in multi vortex shear flow field ». Journal of Physics : Conference Series 2441, n^o 1 (1 mars 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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Yin, Zegao, Qianqian Jia, Yuan Li, Yanxu Wang et Dejun Yang. « Computational Study of a Vertical Plunging Jet into Still Water ». Water 10, n^o 8 (26 juillet 2018) : 989. http://dx.doi.org/10.3390/w10080989.

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The behavior of a vertical plunging jet was numerically investigated using the coupled Level Set and Volume of Fluid method. The computational results were in good agreement with the experimental results reported in the related literature. Vertical plunging jet characteristics, including the liquid velocity field, air void fraction, and turbulence kinetic energy, were explored by varying the distance between the nozzle exit and the still water level. It was found that the velocity at the nozzle exit plays an unimportant role in the shape and size of ascending bubbles. A modified prediction equation between the centerline velocity ratio and the axial distance ratio was developed using the data of the coupled Level Set and Volume of Fluid method, and it showed a better predicting ability than the Level Set and Mixture methods. The characteristics of turbulence kinetic energy, including its maximum value location and its radial and vertical distribution, were also compared with that of submerged jets.

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Taqieddin, Amir, Yuxuan Liu, Akram N. Alshawabkeh et Michael R. Allshouse. « Computational Modeling of Bubbles Growth Using the Coupled Level Set—Volume of Fluid Method ». Fluids 5, n^o 3 (23 juillet 2020) : 120. http://dx.doi.org/10.3390/fluids5030120.

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Understanding the generation, growth, and dynamics of bubbles as they absorb or release dissolved gas in reactive flows is crucial for optimizing the efficiency of electrochemically gas-evolving systems like alkaline water electrolysis or hydrogen production. To better model these bubbly flow systems, we use a coupled level set and volume of fluid approach integrated with a one-fluid transport of species model to study the dynamics of stationary and rising bubbles in reactive two-phase flows. To accomplish this, source terms are incorporated into the continuity and phase conservation equations to allow the bubble to grow or shrink as the species moves through the interface. Verification of the hydrodynamics of the solver for non-reactive systems demonstrates the requisite high fidelity interface capturing and mass conservation necessary to incorporate transport of species. In reactive systems where the species impacts the bubble volume, the model reproduces the theoretically predicted and experimentally measured diffusion-controlled growth rate (i.e., R(t)∝t0.5). The model is then applied to rising bubbles to demonstrate the impact of transport of species on both the bubble velocity and shape as well as the concentration field in its wake. This improved model enables the incorporation of electric fields and chemical reactions that are essential for studying the physicochemical hydrodynamics in multiphysics systems.

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Son, Gihun, et Nahmkeon Hur. « A COUPLED LEVEL SET AND VOLUME-OF-FLUID METHOD FOR THE BUOYANCY-DRIVEN MOTION OF FLUID PARTICLES ». Numerical Heat Transfer, Part B : Fundamentals 42, n^o 6 (décembre 2002) : 523–42. http://dx.doi.org/10.1080/10407790260444804.

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Cheng, Hongping. « Application of Motion Interface Tracking CVOFLS Method to Zalesak Disk Problem ». Highlights in Science, Engineering and Technology 35 (11 avril 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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Liu, An, Dongliang Sun, Bo Yu, Jinjia Wei et Zhizhu Cao. « An adaptive coupled volume-of-fluid and level set method based on unstructured grids ». Physics of Fluids 33, n^o 1 (1 janvier 2021) : 012102. http://dx.doi.org/10.1063/5.0031737.

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Shao, Changxiao, Shian Yuan et Kun Luo. « A generalized coupled level set/volume-of-fluid/ghost fluid method for detailed simulation of gas-liquid flows ». Journal of Computational Physics 487 (août 2023) : 112158. http://dx.doi.org/10.1016/j.jcp.2023.112158.

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Haghshenas, Majid, James A. Wilson et Ranganathan Kumar. « Algebraic coupled level set-volume of fluid method for surface tension dominant two-phase flows ». International Journal of Multiphase Flow 90 (avril 2017) : 13–28. http://dx.doi.org/10.1016/j.ijmultiphaseflow.2016.12.002.

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Dianat, M., M. Skarysz et A. Garmory. « A Coupled Level Set and Volume of Fluid method for automotive exterior water management applications ». International Journal of Multiphase Flow 91 (mai 2017) : 19–38. http://dx.doi.org/10.1016/j.ijmultiphaseflow.2017.01.008.

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Yang, Xiaofeng, Ashley J. James, John Lowengrub, Xiaoming Zheng et Vittorio Cristini. « An adaptive coupled level-set/volume-of-fluid interface capturing method for unstructured triangular grids ». Journal of Computational Physics 217, n^o 2 (septembre 2006) : 364–94. http://dx.doi.org/10.1016/j.jcp.2006.01.007.

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Wang, Tai, Huixiong Li, Yongchang Feng et Dongxiao Shi. « A coupled volume-of-fluid and level set (VOSET) method on dynamically adaptive quadtree grids ». International Journal of Heat and Mass Transfer 67 (décembre 2013) : 70–73. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2013.08.006.

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Albadawi, A., D. B. Donoghue, A. J. Robinson, D. B. Murray et Y. M. C. Delauré. « Influence of surface tension implementation in Volume of Fluid and coupled Volume of Fluid with Level Set methods for bubble growth and detachment ». International Journal of Multiphase Flow 53 (juillet 2013) : 11–28. http://dx.doi.org/10.1016/j.ijmultiphaseflow.2013.01.005.

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Chakraborty, I., M. Rubio-Rubio, A. Sevilla et J. M. Gordillo. « Numerical simulation of axisymmetric drop formation using a coupled level set and volume of fluid method ». International Journal of Multiphase Flow 84 (septembre 2016) : 54–65. http://dx.doi.org/10.1016/j.ijmultiphaseflow.2016.04.002.

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Cao, Baixu, Lina Bai, Zhaochen Hu et Shaobai Li. « Bubble Formation in Yield-Stress Fluids Using a Coupled Level-Set and Volume-of-Fluid Method ». ACS Omega 5, n^o 37 (11 septembre 2020) : 24011–17. http://dx.doi.org/10.1021/acsomega.0c03390.

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Sun, D. L., et W. Q. Tao. « A coupled volume-of-fluid and level set (VOSET) method for computing incompressible two-phase flows ». International Journal of Heat and Mass Transfer 53, n^o 4 (janvier 2010) : 645–55. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2009.10.030.

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Ngo, Long Cu, Hyoung Gwon Choi et Kyoungsik Chang. « A coupled level set/volume of fluid method for simulation of two-phase flow on unstructured grids ». Journal of Mechanical Science and Technology 35, n^o 2 (28 janvier 2021) : 625–34. http://dx.doi.org/10.1007/s12206-021-0122-2.

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Wang, Zhaoyuan, Jianming Yang, Bonguk Koo et Frederick Stern. « A coupled level set and volume-of-fluid method for sharp interface simulation of plunging breaking waves ». International Journal of Multiphase Flow 35, n^o 3 (mars 2009) : 227–46. http://dx.doi.org/10.1016/j.ijmultiphaseflow.2008.11.004.

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Balcázar, Néstor, Oriol Lehmkuhl, Lluís Jofre, Joaquim Rigola et Assensi Oliva. « A coupled volume-of-fluid/level-set method for simulation of two-phase flows on unstructured meshes ». Computers & ; Fluids 124 (janvier 2016) : 12–29. http://dx.doi.org/10.1016/j.compfluid.2015.10.005.

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Cao, Zhizhu, Dongliang Sun, Bo Yu et Jinjia Wei. « A coupled volume of fluid and level set method based on analytic PLIC for unstructured quadrilateral grids ». Numerical Heat Transfer, Part B : Fundamentals 73, n^o 4 (3 avril 2018) : 189–205. http://dx.doi.org/10.1080/10407790.2018.1454758.

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