Articles de revues : « VOF simulations »

1

Lubin, Pierre, et Stéphane Glockner. « NUMERICAL SIMULATIONS OF BREAKING SOLITARY WAVES ». Coastal Engineering Proceedings 1, n^o 33 (28 septembre 2012) : 59. http://dx.doi.org/10.9753/icce.v33.waves.59.

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This paper presents the application of a parallel numerical code to breaking solitary waves impacting a seawall structure. The three-dimensional Navier-Stokes equations are solved in air and water, coupled with a subgrid-scale model to take turbulence into account. We compared three numerical methods for the free-surface description, using the classical VOF-PLIC and VOF-TVD methods, and an original VOF-SM method recently developed in our numerical tool (Vincent et al., 2010). Some experimental data for solitary waves impinging and overtopping coastal structures are available in literature (Hsiao et al., 2010). Solitary waves are often used to model tsunami behaviors because of their hydrodynamic similarities. From a numerical point of view, it allows shorter CPU time simulations, as only one wave breaks. Here we apply the model to simulate three-dimensional solitary waves and compare qualitatively our results with the experimental data. We investigate three configurations of solitary waves impinging and overtopping an impermeable seawall on a 1:20 sloping beach.

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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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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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Spitzenberger, Andy, Sebastian Neumann, Martin Heinrich et Rüdiger Schwarze. « Particle detection in VOF-simulations with OpenFOAM ». SoftwareX 11 (janvier 2020) : 100382. http://dx.doi.org/10.1016/j.softx.2019.100382.

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Yu, Qun, Xiao Dong Hu, Long Huan Huang et Yue Lin. « Optimum Design and Analysis of Metal Delivery System for Magnesium Alloy Plates with Twin-Roll Casting Process ». Applied Mechanics and Materials 395-396 (septembre 2013) : 1150–53. http://dx.doi.org/10.4028/www.scientific.net/amm.395-396.1150.

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Using physical and numerical simulation method，metal delivery system of twin-roll casting magnesium alloy process was researched. The Anycasting software was used to simulate different flow systems by VOF method. And based on similar principles, an acrylic experimental model with the ratio of 1:1 was designed. The dam’s size and position were optimized by simulations and experiments. The flow distribution is uniform along the horizontal of the casting roller. Numerical simulation and physical simulation are in good coincidence.

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Sato, Kenta, et Shunichi Koshimura. « A LATTICE BOLTZMANN APPROACH FOR THREE-DIMENSIONAL TSUNAMI SIMULATION BASED ON THE PLIC-VOF METHOD ». Coastal Engineering Proceedings, n^o 36 (30 décembre 2018) : 90. http://dx.doi.org/10.9753/icce.v36.papers.90.

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Free surface flow problems occur in numerous disaster simulations, such as tsunamis inland penetration in urban area. Simulation models for these problems have to be non-hydrostatic and three-dimensional because of the strong non-linearity and higher-order physical phenomena. Despite all the progress in the modern computational fluid dynamics, such simulations still present formidable challenges both from numerical and computational cost point of view. The lattice Boltzmann method (LBM) has been attracting attention as an alternative fluid simulation tool to overcome the problems. In current study, LBM for three-dimensional tsunami simulations is developed which are coupled with the piecewise linear interface calculation with the Volume of Fluid (VOF) approach. This model is for an efficient three-dimensional tsunami simulation by a one-fluid formulation, where the lattice Boltzmann equation is assigned to solve for a single virtual fluid. Various benchmark problems are also carried out to validate the utility of the proposed models in term of coastal engineering.

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Wu, Zhi-Yong, Wei-Hua Cai, Guo-Dong Qiu et Yi-Qiang Jiang. « Prediction of Mass Transfer Time Relaxation Parameter for Boiling Simulation on the Shell-Side of LNG Spiral Wound Heat Exchanger ». Advances in Mechanical Engineering 6 (1 janvier 2014) : 275708. http://dx.doi.org/10.1155/2014/275708.

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The objective of this present study is to propose an approach to predict mass transfer time relaxation parameter for boiling simulation on the shell-side of LNG spiral wound heat exchanger (SWHE). The numerical model for the shell-side of LNG SWHE was established. For propane and ethane, a predicted value of mass transfer time relaxation parameter was presented through the equivalent evaporation simulations and was validated by the Chisholm void fraction correlation recommended under various testing conditions. In addition, heat transfer deviations between simulations using the predicted value of mass transfer time relaxation parameter and experiments from Aunan were investigated. The boiling characteristics of SWHE shell-side were also visualized based on the simulations with VOF model. The method of predicting mass transfer time relaxation parameter may be well applicable to various phase change simulations.

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NAKAJIMA, Ryota, Takumi CHIBA, Hirokazu UMEMIYA, Sumihisa ODA et Shunji HOMMA. « Numerical Simulations for Curtain Coating by VOF Method ». JAPANESE JOURNAL OF MULTIPHASE FLOW 33, n^o 4 (7 novembre 2019) : 417–23. http://dx.doi.org/10.3811/jjmf.2019.013.

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Kranjčević, Lado, Luka Grbčić, Matija Mrazović et Siniša Družeta. « Rijeka Bay 3D VOF Costal Flow Model ». Journal of Maritime & ; Transportation Science 3, n^o 3 (juin 2020) : 125–32. http://dx.doi.org/10.18048/2020.00.09.

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3D multiphase flow was analyzed in the area of Rijeka bay in the Adriatic Sea. The necessary morphology data in the range of interest of the coastal bottom area were collected and the spatial surface was created. The functionality of the 3D model was studied in the large area of the realistic stochastic structure of the bottom and the shore. The probability of meteorological conditions and wind impact in the model has been shown. The obtained results give a detailed view of the velocity fields in the horizontal plane of different depths. Numerical simulation was performed in open source program OpenFOAM with Volume of Fluid (VOF) method using the Eulerian approach. For solving this problem interFOAM solver for two incompressible, isothermal, immiscible fluids was used. The resulting simulations showed dominant flow from the western coast of the Krk island to the eastern coast of the Istrian peninsula. Seawater enters the bay through the Srednja Vrata and Tihi Kanal and exits the bay through the Vela Vrata. This research has shown that using a VOF method can be successfully implemented for describing fluid motion in large areas such as bays and oceans.

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Taamneh, Yazan. « Influence of Jordanian zeolite on the performance of a solar still : experiments and CFD simulation studies ». Water Supply 16, n^o 6 (2 juin 2016) : 1700–1709. http://dx.doi.org/10.2166/ws.2016.091.

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Computational fluid dynamics (CFD) simulations were performed for experiments carried out with two identical pyramid-shaped solar stills. One was filled with Jordanian zeolite-seawater and the second was filled with seawater only. This work is focused on CFD analysis validation with experimental data conducted using a model of phase change interaction (evaporation-condensation model) inside the solar still. A volume-of-fluid (VOF) model was used to simulate the inter phase change through evaporation-condensation between zeolite-water and water vapor inside the two solar stills. The effect of the volume fraction of the zeolite particles (0 ≤ ϕ ≤ 0.05) on the heat and distillate yield inside the solar still was investigated. Based on the CFD simulation results, the hourly quantity of freshwater showed a good agreement with the corresponding experimental data. The present study has established the utility of using the VOF two phase flow model to provide a reasonable solution to the complicated inter phase mass transfer in a solar still.

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Ao, Xuefei, Xiaoling Wang, Bin Qiao, Ruijin Li et Ruirui Sun. « Large eddy simulation of the turbulent multiphase flow on sandstone wastewater of hydropower stations in a vortex-type grit chamber ». Canadian Journal of Civil Engineering 42, n^o 8 (août 2015) : 510–20. http://dx.doi.org/10.1139/cjce-2015-0063.

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Vortex-type grit chambers are commonly used for the treatment of high-turbidity sandstone wastewater in hydropower stations. Current researches on vortex-type grit chambers mainly focus on the optimization of the engineering operation parameters. Although there have been many studies on sandstone wastewater simulations in stirred tanks or hydrocyclones predicted by Reynolds-averaged Navier–Stokes, there are few reports on the large eddy simulation (LES) based prediction of the multiphase flows in a vortex-type grit chamber. The rigid-lid approximation is commonly used for free surface movement. The LES can reveal more detailed pulsation features. The volume of fluid (VOF) method can describe the interfacial turbulence characteristics for free surface movement. Thus, the VOF method was used as a surface tracking technique along with LES–Lagrangian model to study the characteristics of gas–liquid–solid multiphase flows. The flow field distributions were analyzed and the micro movement regularities of particles were discussed.

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Lv, Xiao Chong, Ya Jun Yin et Jian Xin Zhou. « Research of the Interpolation Method Applied to the Numerical Simulation of the Casting Filling Process ». Advanced Materials Research 1037 (octobre 2014) : 369–72. http://dx.doi.org/10.4028/www.scientific.net/amr.1037.369.

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With the development of computer technology, casting simulation plays an increasingly important role in foundry production. VOF (Volume of Fluid) method which tracks free surfaces is widely used in casting simulation because it is simple to solve and easy to achieve. However, in the last stage of mold filling process, the solution speed of VOF method is very slow because the space to fill becomes smaller. To solve this problem, interpolation formula is applied to the calculation of temperature field and an interpolation method to calculate the last part of temperature field in mold filling process is presented in this paper. The solution is to calculate temperature field of unfilled grids based on the temperature filed of filled grids at the last stage of filling process. Comparison between the results of interpolation method and theoretical calculation illustrates the rationality of the interpolation temperature field in this paper. Numerical simulations of actual castings indicate that the interpolation method can greatly improve the speed of getting temperature field under a certain accuracy. This paper has important implications to the calculation of numerical simulation in mold filling process.

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Bahadar, Ali. « Volume of Fluid Computations of Gas Entrainment and Void Fraction for Plunging Liquid Jets to Aerate Wastewater ». ChemEngineering 4, n^o 4 (18 octobre 2020) : 56. http://dx.doi.org/10.3390/chemengineering4040056.

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Among various mechanisms for enhancing the interfacial area between gases and liquids, a vertical liquid jet striking a still liquid is considered an effective method. This method has vast industrial and environmental applications, where a significant application of this method is to aerate industrial effluents and wastewater treatment. Despite the huge interest and experimental and numerical efforts made by the academic and scientific community in this topic, there is still a need of further study to realize improved theoretical and computational schemes to narrow the gap between the measured and the computed entrained air. The present study is a numerical attempt to highlight the air being entrained by water jet when it intrudes into a still water surface in a tank by the application of a Volume of Fluid (VOF) scheme. The VOF scheme, along with a piecewise linear interface construction (PLIC) algorithm, is useful to follow the interface of the air and water bubbly plume and thus can provide an estimate of the volume fraction for the gas and the liquid. Dimensionless scaling derived from the Fronde number and Reynolds number along with geometric similarities due to the liquid jet’s length and nozzle diameter have been incorporated to validate the experimental data on air entrainment, penetration and void fraction. The VOF simulations for void fraction and air-water mixing and air jet’s penetration into the water were found more comparable to the measured values than those obtained using empirical and Euler-Euler methods. Although, small overestimates of air entrainment rate compared to the experiments have been found, however, VOF was found effective in reducing the gap between measurements and simulations.

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Pienika, Rodolfo, Gabriel Usera et Helena Ramos. « Simulation of a Hydrostatic Pressure Machine with Caffa3d Solver : Numerical Model Characterization and Evaluation ». Water 12, n^o 9 (28 août 2020) : 2419. http://dx.doi.org/10.3390/w12092419.

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The Hydrostatic Pressure Machine (HPM) is a novel energy converter for micro and pico hydropower that becomes very suitable for installation in channels with very low head, where conventional hydraulic turbines are inadequate or too expensive. Although this technology has been studied through several experimental tests and also by numerical simulations, open source flow solvers have not been used yet. The research team on Computational Fluid Mechanics of IMFIA- Universidad de la República (Uruguay) has been developing a CFD open source solver named caffa3d, which has obtained great results in a few international challenges, although it has not been used yet for free surface flows or turbomachinery simulations. The present work shows the contributions made within caffa3d in order to enable its use for simulating a HPM. The Large Eddy Simulation (LES) method is used to model the turbulence structures of the flow. Sliding Mesh (SM) and Volume of Fluid (VOF) methods were chosen respectively to resolve the rotation of the wheel and the position of the free surface. The SM module was already validated in the past, but the VOF module needed to be validated in the present work through the simulation of free surface over a semicylindrical dam. Finally, the performance of a small 12-straight-blade HPM was simulated with caffa3d, with quite satisfactory results. Some issues of the solver yet need to be solved before other HPM with more complex designs could be studied.

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Němeček, Jiří, et Jiří Němeček. « NUMERICAL SIMULATION OF SLUMP FLOW TEST OF CEMENT PASTE COMPOSITES ». Acta Polytechnica CTU Proceedings 30 (22 avril 2021) : 58–62. http://dx.doi.org/10.14311/app.2021.30.0058.

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This study presents a numerical simulation of the mini-slump flow test performed on the Haegerman table, according to EN 1015-3. The two-dimensional axisymmetrical Volume of fluid (VOF) model is used for the calculation. Various scenarios with the different model set up and boundary conditions were calculated to show how the results are affected. Simulations with different lifting velocities were carried out and compared to the case with instantaneous demolding, which is commonly used in numerical simulations. Also, the effect on results is shown between noslip and specific shear boundary conditions on the mold. The results of simulations indicate that mold lifting should be considered in numerical modeling even if calculation time is highly prolonged. Lifting velocities should not exceed the value of 0.2 m/s in order to maintain laminar flow and stablecalculation.

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Fujihara, Masayuki, Mai Akimoto et Mattashi Izumi. « 3-D Numerical Simulations of Pool-and-Weir Fishways Using VOF ». Journal of Rainwater Catchment Systems 14, n^o 1 (2008) : 69–76. http://dx.doi.org/10.7132/jrcsa.kj00004978344.

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Domagala, Mariusz, Halvor Larsson Aga, Saeed Bikass, Hassan Momeni et Gloria Stenfelt. « CFD Estimation of a Resistance Coefficient for an Egg-Shaped Geometric Dome ». Applied Sciences 12, n^o 21 (25 octobre 2022) : 10780. http://dx.doi.org/10.3390/app122110780.

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In aquaculture, new production technologies are under development and testing. One promising type of technology is the closed floating cage. Egget® is one of these newly developed technologies, which is egg-shaped and vertically floating. One of the challenges is to determine hydrodynamic loads. Therefore, this study focuses on estimating the resistance and the resistance coefficient for steady flow with various velocities and Reynolds numbers on a scaled model. It includes simulations using Computational Fluid Dynamics (CFD) for two depths and experiments in the MarinLab at Western Norway University of Applied Sciences (HVL). As the cage is partially submerged, the simulations are performed using the Volume of Fluid (VOF) technique for modeling free surface flow. The comparison of experimental and simulation results show good agreement.

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Ji, Qiao-ling, Xi-zeng Zhao et Sheng Dong. « Numerical Study of Violent Impact Flow Using a CIP-Based Model ». Journal of Applied Mathematics 2013 (2013) : 1–12. http://dx.doi.org/10.1155/2013/920912.

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A two-phase flow model is developed to study violent impact flow problem. The model governed by the Navier-Stokes equations with free surface boundary conditions is solved by a Constrained Interpolation Profile (CIP)-based high-order finite difference method on a fixed Cartesian grid system. The free surface is immersed in the computation domain and expressed by a one-fluid density function. An accurate Volume of Fluid (VOF)-type scheme, the Tangent of Hyperbola for Interface Capturing (THINC), is combined for the free surface treatment. Results of another two free surface capturing methods, the original VOF and CIP, are also presented for comparison. The validity and utility of the numerical model are demonstrated by applying it to two dam-break problems: a small-scale two-dimensional (2D) and three-dimensional (3D) full scale simulations and a large-scale 2D simulation. Main attention is paid to the water elevations and impact pressure, and the numerical results show relatively good agreement with available experimental measurements. It is shown that the present numerical model can give a satisfactory prediction for violent impact flow.

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Xu, Guang Li. « Investigation on Flow Characteristics of Deposited Water Displaced by Flowing Oil in Hilly Terrain Tube ». Advanced Materials Research 516-517 (mai 2012) : 926–30. http://dx.doi.org/10.4028/www.scientific.net/amr.516-517.926.

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The flow characteristics of deposited water displaced by flowing oil in hilly terrain tube were studied experimentally and numerically. Lab-scale experiments were carried out on the transparent organic glass test loop with I.D. 50 mm to investigate the distributions of oil-water interface by diesel flowing from a lower horizontal test section into the up-inclined test section. Two-dimensional numerical simulation was conducted by VOF model and CSF model based on the test geometrical model. Comparisons of the oil-water interface distribution and the critical superficial oil velocity show that the numerical simulations favorably compare with the measurements.

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Rossano, Viola, et Giuliano De Stefano. « Hybrid VOF–Lagrangian CFD Modeling of Droplet Aerobreakup ». Applied Sciences 12, n^o 16 (19 août 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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Fayed, Hassan, Mustafa Bukhari et Saad Ragab. « Large-Eddy Simulation of a Hydrocyclone with an Air Core Using Two-Fluid and Volume-of-Fluid Models ». Fluids 6, n^o 10 (14 octobre 2021) : 364. http://dx.doi.org/10.3390/fluids6100364.

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Large-eddy simulations have been conducted for two-phase flow (water and air) in a hydrocyclone using Two-Fluid (Euler–Euler) and Volume-of-Fluid (VOF) models. Subgrid stresses are modeled using a dynamic eddy–viscosity model, and results are compared to those using the Smagorinsky model. The effects of grid resolutions on the mean flow and turbulence statistics have been thoroughly investigated. Five block-structured grids of 0.72, 1.47, 2.4, 3.81, and 7.38 million elements have been used for the simulations of Hsieh’s 75 mm hydrocyclone Mean velocity profiles and normal Reynolds stresses have been compared with experimental data. Results of the two-fluid model are in good agreement with those of the VOF model. A fine mesh in the axial and radial directions is necessary for capturing the turbulent vortical structure. Turbulence structures in the hydrocyclone are dominated by helical vortices around the air core. Energy spectra are analyzed at different points in the hydrocyclone, and regions of low turbulent kinetic energy are identified and attributed to stabilizing effects of the swirling velocity component.

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Fayed, Hassan, Mustafa Bukhari et Saad Ragab. « Large-Eddy Simulation of a Hydrocyclone with an Air Core Using Two-Fluid and Volume-of-Fluid Models ». Fluids 6, n^o 10 (14 octobre 2021) : 364. http://dx.doi.org/10.3390/fluids6100364.

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Large-eddy simulations have been conducted for two-phase flow (water and air) in a hydrocyclone using Two-Fluid (Euler–Euler) and Volume-of-Fluid (VOF) models. Subgrid stresses are modeled using a dynamic eddy–viscosity model, and results are compared to those using the Smagorinsky model. The effects of grid resolutions on the mean flow and turbulence statistics have been thoroughly investigated. Five block-structured grids of 0.72, 1.47, 2.4, 3.81, and 7.38 million elements have been used for the simulations of Hsieh’s 75 mm hydrocyclone Mean velocity profiles and normal Reynolds stresses have been compared with experimental data. Results of the two-fluid model are in good agreement with those of the VOF model. A fine mesh in the axial and radial directions is necessary for capturing the turbulent vortical structure. Turbulence structures in the hydrocyclone are dominated by helical vortices around the air core. Energy spectra are analyzed at different points in the hydrocyclone, and regions of low turbulent kinetic energy are identified and attributed to stabilizing effects of the swirling velocity component.

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Liu, Hong, Mao Zhao Xie, Hong Chao Yin et De Qing Wang. « VOF Simulations of Gas Bubbles Motion in a Reciprocally Stirred Flow ». Applied Mechanics and Materials 44-47 (décembre 2010) : 2494–98. http://dx.doi.org/10.4028/www.scientific.net/amm.44-47.2494.

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This paper reports progress in the numerical simulations of movement and the coalescence of two neighbor bubbles (leading and trailing bubble) in a reciprocally stirred liquid flow field. The full Navier-Stokes equations are solved by the volume-of fluid (VOF) method for tracking the interface between the bubble and the liquid flow. A dynamic mesh method was used to predict the gas-liquid flow in a two-dimensional foaming tank. Results indicate that the motion and merge behavior of the bubbles is dominantly influenced by the initial locations and the sizes of the bubbles as well as by the surface tension, while the reciprocating effect is insignificant.

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Liu, Guangshuai, Toraharu Watanabe et Takeshi Shinoda. « Two-phase Flow Analysis for Small-scale Ballast Water Tank Model by Hydraulics Experiment and Simulations ». IOP Conference Series : Earth and Environmental Science 972, n^o 1 (1 janvier 2022) : 012048. http://dx.doi.org/10.1088/1755-1315/972/1/012048.

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Abstract This study is utilizing hydraulics experimental and computational fluid dynamics (CFD) methods to verify the flow phenomenon in the ballast water drainage process and discuss the drainage efficiency. In order to facilitate the analysis of the flow characteristics of ballast water in the ballast tank of a typical bulk carrier, the complex structure is simplified into two simple small-scale models, a single-longitudinal model and a single-transversal model. Both are designed with the scale of 1:10 for the data collection. The experimental results are then validated and verified by conducting a two-phase flow model applied volume of fluid (VOF) method. Based on that result, the use of the VOF method is suitable for the ballast water drainage simulation, so it can be used in large-scale model calculations to predict the drainage efficiency of ballast tanks. In addition, this study also conducts a comparative analysis of two configuration modes of the single-longitudinal model and the single-transversal model, which provides a reference for the design and improvement of complex structures.

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Sukamta, Rama Putrantyo Anwar, Sudarja, Sri Sundari et Mochamad Syamsiro. « Computational Fluid Dynamics of Two-Phase Flow Pressure Gradient of Air-Sodium Chloride and Glucose in Horizontal Capillary Channels ». CFD Letters 14, n^o 1 (11 janvier 2022) : 52–65. http://dx.doi.org/10.37934/cfdl.14.1.5265.

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One of the problems in the two-phase flow is investigating the type of flow pattern that occurs in a mini channel without experimenting first. Computational Fluid Dynamics (CFD) is one way that can be used to predict pressure drop, flow pattern, void fraction, other parameters in fluid flow through a channel of a specific size. This research used the CFD simulations to predict the pressure gradient in a two-phase flow of air-sodium chloride 0.9% and glucose in a horizontal capillary tube with a diameter of 1.6 mm, and length of 70 mm. This research aims to obtain the simulation results of 2D and 3D pressure gradients to validate the experimental data. The simulation was carried out with a variation of the superficial gas velocity 0.1 - 8.3 m / s against the superficial velocity of the liquid constant 0.207 m / s. Simulations were carried out using the Volume of Fluid (VOF) model with the "ANSYS Fluent 2020 R1" software. In 2D and 3D simulations, the gradient values of pressure gradients tend to increase as JG increases. The pressure gradient fluctuates linearly at first, then exponentially from mid-to-end. The findings demonstrate that simulations may properly model physical processes like pattern creation and phase interactions. However, due to several physical elements considered in 3D simulation but missed in 2D simulation, the findings of the 2D and 3D simulations were dramatically different when looking at the pressure gradient values.

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Zhu, Hongbo, Dai Zhou, Zhaolong Han, Jin Ma, Yan Bao et Shixiao Fu. « The Performance Assessment of a Semisubmersible Platform Subjected to Wind and Waves by a CFD/6-DOF Approach ». Shock and Vibration 2020 (19 août 2020) : 1–16. http://dx.doi.org/10.1155/2020/8871409.

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The semisubmersible platform is one of the most important equipment for the exploitation of deep-sea oil and gas. And its survival and operational capacities depend on the towing and motion performances. The present work investigates the properties of different platform component designs based on their towing and motion performances under wind and waves by using an integrated computational fluid dynamics (CFD) method. The joint application of RANS and a VOF/6-DOF solver compiled in a new Fluent UDF Library is adopted for the main calculation. Numerical simulations and results demonstrate that the VOF/6-DOF solver is accurate and stable, which could achieve the same functions as the previous OpenFOAM scheme. In order to acquire a better towing performance, different shapes are suggested for the pontoon end shape, the column cross section, and the brace longitudinal section, respectively. As to the motion response, among all the three design selections, the column cross section has the greatest influence on the whole platform. The simulation results reveal that circle section increases the roll and pitch response and reduces the heave response, to which the square section is adverse.

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Chen, Yujia, Maoxuan Cai, Shixun Zhang, Na Zhang et Wei Cao. « Vacuum Filling Simulation with Combined Lagranian and VOF Method ». Journal of Mechanical Materials and Mechanics Research 5, n^o 1 (30 mars 2022) : 1. http://dx.doi.org/10.30564/jmmmr.v5i1.4511.

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Jetting succeeded by accumulation is the characteristic of the vacuum filling, which is different from the conventional pressure-driven flow. In order to simulate this kind of flow, a three-dimensional theoretical model in terms of incompressible and viscous flow is established, and an iterative method combined with finite element method (FEM) is proposed to solve the flow problem. The Lagranian-VOF method is constructed to trace the jetting and accumulated flow fronts. Based on the proposed model and algorithm, a simulation program is developed to predict the velocity, pressure, temperature, and advancement progress. To validate the model and algorithm, a visual experimental equipment for vacuum filling is designed and construted. The vacuum filling experiments with different viscous materials and negative pressures were conducted and compared the corresponding simulations. The results show the flow front shape closely depends on the fluid viscosity and less relates to the vacuum pressure.

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Ziemińska-Stolarska, Aleksandra, Andrzej Polańczyk et Ireneusz Zbiciński. « 3-D CFD simulations of hydrodynamics in the Sulejow dam reservoir ». Journal of Hydrology and Hydromechanics 63, n^o 4 (1 décembre 2015) : 334–41. http://dx.doi.org/10.1515/johh-2015-0033.

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AbstractThis paper reports the processes by which a single-phase 3-D CFD model of hydrodynamics in a 17-km-long dam reservoir was developed, verified and tested. A simplified VOF model of flow was elaborated to determine the effect of wind on hydrodynamics in the lake. A hexahedral mesh with over 17 million elements and a k-ω SST turbulence model were defined for single-phase simulations in steady-state conditions. The model was verified on the basis of the extensive flow measurements (StreamPro ADCP, USA). Excellent agreement (average error of less than 10%) between computed and measured velocity profiles was found. The simulation results proved a strong effect of wind on hydrodynamics in the lake, especially on the development of the water circulation pattern in the lacustrine zone.

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Han, Shuang, Runhua Yang, Chaobo Li et Lixin Yang. « The Wettability and Numerical Model of Different Silicon Microstructural Surfaces ». Applied Sciences 9, n^o 3 (8 février 2019) : 566. http://dx.doi.org/10.3390/app9030566.

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Wettability is an important property of solid surfaces and is widely used in many industries. In this work, seven silicon microstructure surfaces were made by plasma immersion ion implantation (PIII) technology. The experimental contact angles and theoretical contact angles of various surfaces were compared, which indicated that the classical theory had great limitations in predicting the static contact angles of complex structures. A parameterized microstructure surface was established by computational fluid dynamics (CFD) with a volume-of-fluid (VOF) model to analyze the reasons for the differences between experimental and theoretical contact angles. Comparing the results of experiments and simulations, it was found that the VOF model can simulate the contact angle of these surfaces very well. The geometrical models of the different microstructures were simplified, and waveforms of the surfaces were obtained.

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Ii, Satoshi, Xiaobo Gong, Kazuyasu Sugiyama, Jinbiao Wu, Huaxiong Huang et Shu Takagi. « A Full Eulerian Fluid-Membrane Coupling Method with a Smoothed Volume-of-Fluid Approach ». Communications in Computational Physics 12, n^o 2 (août 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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Bedram, Ahmad, et Ali Moosavi. « Breakup of Droplets in Micro and Nanofluidic T-Junctions ». Applied Mechanics and Materials 110-116 (octobre 2011) : 3673–78. http://dx.doi.org/10.4028/www.scientific.net/amm.110-116.3673.

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We employ numerical simulations to investigate the breakup of droplets in micro-and nanoscale T junctions which are used to produce small droplets from a large droplet. A Volume Of Fluid (VOF) method was used and for verifying the accuracy of simulation the results compared with two analytical researches. Our results reveal that breakup time and breakup length of the droplets play important roles in handling these systems optimally. Our results also indicate that for nanoscale T-junctions by increasing the capillary number the performance increases while for the micro-scale systems there is a specific capillary number for which the system is in its optimum condition.

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Zandi, Reza, Khosro Lari et Mohammad Najafzadeh. « Optimum Coastal Slopes Exposed to Waves : Experimental and Numerical Study ». Water 15, n^o 2 (16 janvier 2023) : 366. http://dx.doi.org/10.3390/w15020366.

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In this research, experimental and numerical studies of water waves in a wave tank are analyzed and how to find the optimum beach slope for numerical simulation is also investigated. First, with the aid of a wave tank (flap type), waves with different wave amplitudes are created in the laboratory, and data of generated waves are measured by different wave probes. Then, numerical simulations of the wave tank and waves with different wave amplitudes are performed in Ansys Fluent industrial software. The VOF method is used to model two-phase flow. The results of experimental and numerical simulations are compared and examined. Moreover, the effects of the beach slope on the simulation are analyzed and compared with the experimental results to obtain the best slope. The results show that the numerical simulation, by using the appropriate beach slope, can properly model the experimental results with a low CPU time. Additionally, the 1:5 beach slope is considered the best slope that can dampen the energy of the waves and prevent their reflection.

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Roy Biswas, Tirtha, Subhasish Dey et Dhrubajyoti Sen. « Undular Hydraulic Jumps : Critical Analysis of 2D RANS-VOF Simulations ». Journal of Hydraulic Engineering 147, n^o 11 (novembre 2021) : 06021017. http://dx.doi.org/10.1061/(asce)hy.1943-7900.0001939.

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Afkhami, S., et M. Bussmann. « Height functions for applying contact angles to 2D VOF simulations ». International Journal for Numerical Methods in Fluids 57, n^o 4 (2008) : 453–72. http://dx.doi.org/10.1002/fld.1651.

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Afkhami, S., et M. Bussmann. « Height functions for applying contact angles to 3D VOF simulations ». International Journal for Numerical Methods in Fluids 61, n^o 8 (20 novembre 2009) : 827–47. http://dx.doi.org/10.1002/fld.1974.

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Biausser, Benjamin, Stephan Guignard, Richard Marcer et Philippe Fraunié. « 3D two phase flows numerical simulations by SL-VOF method ». International Journal for Numerical Methods in Fluids 45, n^o 6 (25 mai 2004) : 581–604. http://dx.doi.org/10.1002/fld.708.

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BÉG, O. ANWAR, M. M. RASHIDI, M. AKBARI et A. HOSSEINI. « COMPARATIVE NUMERICAL STUDY OF SINGLE-PHASE AND TWO-PHASE MODELS FOR BIO-NANOFLUID TRANSPORT PHENOMENA ». Journal of Mechanics in Medicine and Biology 14, n^o 01 (février 2014) : 1450011. http://dx.doi.org/10.1142/s0219519414500110.

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A computational fluid dynamics (CFD) simulation of laminar convection of Al 2 O 3–water bio-nanofluids in a circular tube under constant wall temperature conditions was conducted, employing a single-phase model and three different two-phase models (volume of fluid (VOF), mixture and Eulerian). The steady-state, three-dimensional flow conservation equations were discretised using the finite volume method (FVM). Several parameters such as temperature, flow field, skin friction and heat transfer coefficient were computed. The computations showed that CFD predictions with the three different two-phase models are essentially the same. The CFD simulations also demonstrated that single-phase and two-phase models yield the same results for fluid flow but different results for thermal fields. The two-phase models, however, achieved better correlation with experimental measurements. The simulations further showed that heat transfer coefficient distinctly increases with increasing nanofluid particle concentration. The physical properties of the base fluid were considered to be temperature-dependent, while those of the solid particles were constant. Grid independence tests were also included. The simulations have applications in novel biomedical flow processing systems.

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Bujor, Alexandra Madalina, Andreea Mandru et Florin Pacuraru. « Numerical simulation of the flow around kayak hull ». Analele Universităţii "Dunărea de Jos" din Galaţi Fascicula XI Construcţii navale/ Annals of "Dunărea de Jos" of Galati Fascicle XI Shipbuilding 45 (3 décembre 2022) : 113–18. http://dx.doi.org/10.35219/annugalshipbuilding/2022.45.13.

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The purpose of this study was to determine the total resistance and investigate the flow around a full-scale kayak. Utilizing Computational Fluid Dynamics(CFD), it was deter-mined how the presence of a rudder affects the kayak hydrodynamic performance. To an-alyse the flow, computational fluid dynamics based on the RANS-VOF solver was em-ployed. The fluid volume approach and the k-ω turbulence model were used in two-phase steady flow simulations around the kayak hulls.

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von Boetticher, Albrecht, Jens M. Turowski, Brian W. McArdell, Dieter Rickenmann et James W. Kirchner. « DebrisInterMixing-2.3 : a finite volume solver for three-dimensional debris-flow simulations with two calibration parameters – Part 1 : Model description ». Geoscientific Model Development 9, n^o 9 (31 août 2016) : 2909–23. http://dx.doi.org/10.5194/gmd-9-2909-2016.

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Abstract. Here, we present a three-dimensional fluid dynamic solver that simulates debris flows as a mixture of two fluids (a Coulomb viscoplastic model of the gravel mixed with a Herschel–Bulkley representation of the fine material suspension) in combination with an additional unmixed phase representing the air and the free surface. We link all rheological parameters to the material composition, i.e., to water content, clay content, and mineral composition, content of sand and gravel, and the gravel's friction angle; the user must specify only two free model parameters. The volume-of-fluid (VoF) approach is used to combine the mixed phase and the air phase into a single cell-averaged Navier–Stokes equation for incompressible flow, based on code adapted from standard solvers of the open-source CFD software OpenFOAM. This effectively single-phase mixture VoF method saves computational costs compared to the more sophisticated drag-force-based multiphase models. Thus, complex three-dimensional flow structures can be simulated while accounting for the pressure- and shear-rate-dependent rheology.

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Liu, Ting Ting, Wei Su, Tao Yang, Bin Han et Chao Wang. « Research on Characteristics of Mercury Droplet Flow in Micro Acceleration Switch ». Key Engineering Materials 562-565 (juillet 2013) : 328–33. http://dx.doi.org/10.4028/www.scientific.net/kem.562-565.328.

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Unlike the solid-solid contact of traditional micro acceleration switch, liquid metal can be utilized to solve the disadvantage of solid-solid contact, such as contact wear and signal bounce. Liquid-metal micro switches have demonstrated no contact bounce, low switch-on time, low contact resistance, long life, and the capability to handle large currents. So the liquid-metal micro acceleration switches have attracted researcher’s attentions increasingly. To investigate the flow characteristics of mercury droplet in micro acceleration switch, this paper establishes numerical models of micro acceleration switch by using FLUENT. The effect of contact angle, droplet volume and temperature are discussed in this paper. Based on the VOF-CSF model of FLUENT, a serial of simulations were performed. The simulation results show that the influence of contact angle and droplet volume on flow characteristics is serious, and the influence of temperature is small. As compared with theoretical analysis, simulations are in good agreement with theoretical analysis.

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Wu, C. S., et D. L. Young. « Interface Reconstruction with Split Lagrangian Advection for Two-Dimensional Interfacial Flows ». Journal of Mechanics 29, n^o 2 (20 décembre 2012) : 253–62. http://dx.doi.org/10.1017/jmech.2012.144.

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AbstractThis paper contributes to propose a 2D practical interface tracking algorithm of volume-of-fluid (VOF) method through the improved interface reconstruction, namely using both mixed Youngs centered column method (MYCCM) and the Lagrangian split advection scheme. A computationally efficiency and second-order accuracy for interface reconstruction method is presented and approximated by heuristic algorithms based on the piecewise linear interface calculation (PLIC) concept. The method can be accurately estimated by a regular structured mesh without any geometrical modifications. Besides, a linear mapping technique is implemented to improve the efficiency of numerical simulations with regard to the approximation for capturing the interface. The computational tests include widely used benchmark cases, such as the solid-body translations and rotations and the swirled single vortex of fluid body. Its performances of the improved algorithm are compared against other classical VOF advection methods. Good results are obtained by using present algorithm.

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Cwudziński, A., J. Jowsa et P. Przegrałek. « Interaction of Liquid Steel with Mould Flux in Continuous Casting Bloom Mould - Numerical Simulations and Industrial Experiences ». Archives of Metallurgy and Materials 61, n^o 4 (1 décembre 2016) : 2013–20. http://dx.doi.org/10.1515/amm-2016-0325.

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Abstract The device under examination is a mould of a capacity of 0.5 Mg and with inner cross-section of 280×400 mm. The virtual model of the facility under investigation was made using Gambit, DesignModeler and Meshing programs. Computer simulation of the liquid steel flow and mould flux behaviour in turbulent motion conditions was done using the Ansys-Fluent® computer program. On the basis of earlier researches the volume of fluid (VOF) model was applied. Based on computer simulations carried out, steel flow and flux behaviour fields and curves of flux mould entrainment concentration were obtained. The results obtained from numerical simulation were compared with the data obtained during bloom casting under industrial conditions. Based on the obtained information on the interaction of steel with mould flux, the region was determined, in which conditions likely to favour the entrainment of slag portions into the forming bloom exist.

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von Boetticher, A., J. M. Turowski, B. W. McArdell, D. Rickenmann et J. W. Kirchner. « DebrisInterMixing-2.3 : a Finite Volume solver for three dimensional debris flow simulations based on a single calibration parameter – Part 1 : Model description ». Geoscientific Model Development Discussions 8, n^o 8 (13 août 2015) : 6349–78. http://dx.doi.org/10.5194/gmdd-8-6349-2015.

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Abstract. Here we present a three-dimensional fluid dynamic solver that simulates debris flows as a mixture of two phases (gravel and fine material suspension) with a third unmixed phase representing the air and the free surface. We link all rheological parameters to the material composition, i.e., to water content, clay content and mineral composition, content of sand and gravel, and the gravel's friction angle; the user must specify only a single free model parameter. The Volume-Of-Fluid (VOF) approach is used to combine the three phases into a single cell-averaged Navier–Stokes equation for incompressible flow, based on code adapted from standard solvers of the Open-Source CFD software OpenFOAM. We present a stable implementation of a Coulomb-Viscoplastic model that represents the pressure-dependent flow behavior of the granular phase, and a Herschel–Bulkley representation of the interstitial fluid. The VOF method saves computational costs compared to drag-force based multiphase models. Thus depth-averaging is not necessary and complex three-dimensional flow structures can be simulated.

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Raynal, Ludovic, et Isabelle Harter. « Studies of gas–liquid flow through reactors internals using VOF simulations ». Chemical Engineering Science 56, n^o 21-22 (novembre 2001) : 6385–91. http://dx.doi.org/10.1016/s0009-2509(01)00220-2.

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Gunjal, Prashant R., Vivek V. Ranade et Raghunath V. Chaudhari. « Dynamics of drop impact on solid surface : Experiments and VOF simulations ». AIChE Journal 51, n^o 1 (2004) : 59–78. http://dx.doi.org/10.1002/aic.10300.

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Pernod, Laetitia, Matthieu Sacher, Jeroen Wackers, Benoit Augier et Patrick Bot. « Free-Surface Effects on Two-Dimensional Hydrofoils by RANS-VOF Simulations ». Journal of Sailing Technology 8, n^o 01 (27 janvier 2023) : 24–38. http://dx.doi.org/10.5957/jst/2023.8.2.24.

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Foiling yachts and crafts are both very sensitive to the flying height in terms of stability and performance, raising the scientific issue of the influence of the free-surface when the foil is at low submergence. This work presents numerical simulations of a 2D hydrofoil section NACA0012 at 5° angle of attack in the vicinity of the free-surface, for different values of the submergence depth, for a chord-based Froude number of 0.571 and a Reynolds number of 159,000. Unsteady-Reynolds Averaged Navier-Stokes (URANS) equations are solved with a mixture model to capture the free surface (Volume Of Fluid method), and using an automatic grid refinement. Verification of the numerical model and validation with data from the literature are presented. Deformation of the free surface and alteration of the hydrodynamic forces compared to the deep immersion case are observed for a submergence depth-to-chord ratio ℎ/𝑐 lower than 2. The foil drag increases up to more than three times the infinite-depth value at ℎ/𝑐≈0.5. The lift force slightly increases until ℎ/𝑐 around 1, and then decreases sharply. For ℎ/𝑐<0.5, the pressure field around the foil is totally modified and the lift is swapped to downward. The study highlights the importance of considering the effect of finite submergence to compute foils’ hydrodynamic forces, for example to be used in Velocity Prediction Programs (VPP) of foiling crafts.

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Gao, Shian, et Chimaobi Dennar. « Computational Simulation of Multi-Product Flow in an Oil Transportation Pipeline ». Applied Mechanics and Materials 590 (juin 2014) : 161–65. http://dx.doi.org/10.4028/www.scientific.net/amm.590.161.

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This paper presents a predictive investigation using Computational Fluid Dynamic (CFD) techniques focusing on the study of contamination that occurs between different products in an oil pipeline under normal operating conditions. The use of CFD techniques yields detailed flow conditions including the velocity fields, phase distribution and interface evolution, which can provide valuable information to the oil industry especially in the distribution of oil products. The Volume of Fluid (VOF) model is used in this project in a pipe with two fluids. Simulation results show the interface evolution between the two fluids and how it is affected by properties such as viscosity ratio and pressure difference. Operational data from the Nigerian National Petroleum Corporation was obtained to validate the results from the simulations.

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Bhushan, Shanti, Oumnia El Fajri, Graham Hubbard, Bradley Chambers et Christopher Kees. « Assessment of Numerical Methods for Plunging Breaking Wave Predictions ». Journal of Marine Science and Engineering 9, n^o 3 (2 mars 2021) : 264. http://dx.doi.org/10.3390/jmse9030264.

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This study evaluates the capability of Navier–Stokes solvers in predicting forward and backward plunging breaking, including assessment of the effect of grid resolution, turbulence model, and VoF, CLSVoF interface models on predictions. For this purpose, 2D simulations are performed for four test cases: dam break, solitary wave run up on a slope, flow over a submerged bump, and solitary wave over a submerged rectangular obstacle. Plunging wave breaking involves high wave crest, plunger formation, and splash up, followed by second plunger, and chaotic water motions. Coarser grids reasonably predict the wave breaking features, but finer grids are required for accurate prediction of the splash up events. However, instabilities are triggered at the air–water interface (primarily for the air flow) on very fine grids, which induces surface peel-off or kinks and roll-up of the plunger tips. Reynolds averaged Navier–Stokes (RANS) turbulence models result in high eddy-viscosity in the air–water region which decays the fluid momentum and adversely affects the predictions. Both VoF and CLSVoF methods predict the large-scale plunging breaking characteristics well; however, they vary in the prediction of the finer details. The CLSVoF solver predicts the splash-up event and secondary plunger better than the VoF solver; however, the latter predicts the plunger shape better than the former for the solitary wave run-up on a slope case.

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Xiang, Ai Shuang, Xiao Ming Wang et Song Lin Xu. « Feed Rate on Velocity Field of Liquid Film in a Wiped Film Molecular Distillatory ». Advanced Materials Research 560-561 (août 2012) : 46–51. http://dx.doi.org/10.4028/www.scientific.net/amr.560-561.46.

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Effect of feed flow rate on velocity field of evaporating liquid film in a wiped film molecular distillatory was studied with a computational fluid dynamics (CFD) method. Three assumptions were introduced in order to simplify modeling processes. According to our previous study, the RNG k-εturbulent model treating near-wall flow was properly used in this simulation. The volume of fluid (VOF) multiphase model was also applied to track the liquid-gas surface. A near-wall modeling method, enhanced wall treatment, was used to consider the effect of walls. Simulations were carried out in rotating coordinate system. All simulation results are reasonably identical with real situation and were discussed in several aspects. It was concluded that increment of feed flow rate would reduce the turbulence of liquid film on the evaporator surface and then reduce the evaporation rate.

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Bozorgnia, Mehrdad, et Jiin-Jen Lee. « COMPUTATIONAL FLUID DYNAMIC ANALYSIS OF HIGHWAY BRIDGES EXPOSED TO HURRICANE WAVES ». Coastal Engineering Proceedings 1, n^o 33 (14 décembre 2012) : 70. http://dx.doi.org/10.9753/icce.v33.waves.70.

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In present paper, numerical code STAR CCM+ by CD-adapco which works based on compressible two-phase Navier Stokes equations is used to evaluate hydrodynamic forces exerted on prototype of I10 Bridge over Escambia Bay which was extensively damaged during Hurricane Ivan. Volume of Fluid (VOF) is used to capture dynamic free surface which is well suited for simulating complex discontinuous free surface associated with wave-deck interactions. 2D and 3D models were setup and properly configured. Simulations were conducted on High performance Computing and Communication Center (HPCC) at University of Southern California. Simulation results are compared to experimental data available from Hinsdale Wave Laboratory at Oregon State University. Comparison of experimental data to simulation results show the importance of proper mesh size and time step choice on accuracy of horizontal and vertical hydrodynamic force predictions applied to bridge superstructure.

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