Sina Alavi, Mohammad Passandideh-Fard^*

Frontiers in Heat and Mass Transfer, Vol.2, No.2, pp. 1-9, 2011, DOI:10.5098/hmt.v2.2.3007

Abstract In this paper, a numerical study is performed to investigate the effects of thermal shrinkage on the deposition of molten particles on a substrate in a thermal spray process using the Volume-of-Fluid (VOF) method. Thermal shrinkage is a phenomenon caused by the variation of density during cooling and solidification of a molten metal. The Navier-Stokes equations along with the energy equation including phase change are solved using a 2D/axisymmetric mesh. The VOF method is used to track the free surface of molten particles, and an enthalpy-porosity formulation is used to model solidification. For the normal impact of tin particles in… More >

Meng Jia, Mingjun Pang^*

Frontiers in Heat and Mass Transfer, Vol.21, pp. 337-366, 2023, DOI:10.32604/fhmt.2023.044286

Abstract The interphase mass, heat transfer efficiency, and flow resistance are strongly dependent on bubble size in gasliquid two-phase systems, so it is very important for engineering applications to effectively control bubble size. In this paper, the formation, growth, and detachment of single bubbles in Newtonian liquids based on capillary needles were studied in detail using a volume of fluid method. The authors investigated the effects of gas injection velocity, gravitational level, surface tension coefficient, needle radius, and liquid−phase properties (liquid viscosity and density) on the process of bubble generation, and the effects of the above factors on bubble shape, detachment… More >

Yunxing Zhang, Shan Ma, Kangping Liao, Wenyang Duan^*

CMES-Computer Modeling in Engineering & Sciences, Vol.128, No.1, pp. 43-64, 2021, DOI:10.32604/cmes.2021.014847

Abstract In this study, a numerical model for simulating two-phase flow is developed. The Cartesian grid with Adaptive Mesh Refinement (AMR) is adopted to reduce the computational cost. An explicit projection method is used for the time integration and the Finite Difference Method (FDM) is applied on a staggered grid for the discretization of spatial derivatives. The Volume of Fluid (VOF) method with Piecewise-Linear Interface Calculation (PLIC) is extended to the AMR grid to capture the gas-water interface accurately. A coarse-fine interface treatment method is developed to preserve the flux conservation at the interfaces. Several two-dimensional (2D) and three-dimensional (3D) benchmark… More >

Dongling Yu¹, Huiling Zhang¹, Xu Zeng¹, Dahai Liao^1,*, Nanxing Wu^2,*

FDMP-Fluid Dynamics & Materials Processing, Vol.17, No.3, pp. 569-586, 2021, DOI:10.32604/fdmp.2021.014711

Abstract In order to reveal the intrinsic fluid-dynamic mechanisms of a pressure-swirl nozzle used for Si₃N₄ dry granulation, and effectively predict its external spray characteristics, the dynamics of air-atomized liquid two-phase flow is analyzed using a VOF (Volume of Fraction) method together with the modified realizable k-ε turbulence model. The influence of nozzle orifice shape on velocity distribution, pressure distribution is studied. The results show that the pressure difference in a convergent conical nozzle is the largest with a hollow air core being formed in the nozzle. The corresponding velocity of atomized liquid at nozzle orifice is the largest. Using a… More >

Shuifen Zhan^{1, 2, 3}, Mingchao Wang^{2, *}, Min Wang^{5, *}, Qianqian Shao⁴, Zefang Zhang³, Wenxin Jiang², Xuemin Chen¹

CMES-Computer Modeling in Engineering & Sciences, Vol.123, No.1, pp. 217-235, 2020, DOI:10.32604/cmes.2020.08289

Abstract Considering the accidents of ships for dangerous chemicals transportation in inland rivers, a numerical method for the simulation of the leakage and diffusion processes of dangerous chemicals in inland rivers is proposed in this paper. Geographic information, such as rivers and buildings in the model, is obtained through Google Earth and structures of rivers and buildings are described by Auto CAD. In addition, the Fluent is adopted to simulate the leakage and diffusion processes of the dangerous chemicals where the standard k-ε model is used to calculate the turbulent flow. Considering the interaction between chemicals and water, the VOF method… More >

Tawfiq Chekifi^1,*

FDMP-Fluid Dynamics & Materials Processing, Vol.15, No.5, pp. 545-555, 2019, DOI:10.32604/fdmp.2019.01793

Abstract Numerical simulation using Ansys Fluent code is performed, to investigate droplet generation in cross-junction based VOF method. Droplets of water are generated by the shear stress applied by continuous phase (oil), two configurations of cross-junction are suggested; the first is a simple model no modification is performed at the outer channel, while the second model is characterized by a lateral obstacle. we study the effect of velocity ratio, viscous parameter, interfacial tension, flow condition on droplet size and frequency, the effect of lateral obstacles on droplets generation is also focused and analysed. The numerical simulations showed that the velocity ratio… More >

Tawfiq Chekifi^{1, *}, Brahim Dennai², Rachid Khelfaoui²

FDMP-Fluid Dynamics & Materials Processing, Vol.13, No.3, pp. 173-187, 2017, DOI:10.3970/fdmp.2017.013.173

Abstract Recently, modeling immiscible fluids such as oil and water have been a classical research topic. Droplet-based microfluidics presents a unique platform for mixing, reaction, separation, dispersion of drops and many other functions. In this paper, we suggest a numerical CFD study of microfluidic oscillator with two different lengths of feedback loop. In order to produce simultaneous droplets of gasoil on water, a typical geometry that includes double T-junction is connected to the fluidic oscillator. Droplets production is computed by volume-of-fluid method (VOF). Flow oscillations of droplets were triggered by the Coanda effect of jet flow. The aim of work is… More >

Lin LU, Bin TENG, Bing CHEN

The International Conference on Computational & Experimental Engineering and Sciences, Vol.19, No.4, pp. 133-134, 2011, DOI:10.3970/icces.2011.019.133

Abstract This work describes the numerical implements of a two-dimensional viscous numerical wave flume, which is based on the Finite Element Method (FEM), Computational lagrangian-Eulerian Advection Remap Volume of Fluid Method (CLEAR-VOF), internal wave generation and artificial wave damping technique. Owning to the inherent consistence of CLEAR-VOF with FEM, the present numerical model allows the simulations of wave propagation and interaction with structures to be simulated with irregular mesh partition. The present numerical wave flume is validated by several applications in comparisons with available experimental data and numerical results, including the problems of standing wave trains in front of vertical wall,… More >

Jr-Ming Miao^1,2, Fuh-Lin Lih³, Yi-Chun Liou⁴, Hsiu-Kai Chen¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.12, No.1, pp. 33-34, 2009, DOI:10.3970/icces.2009.012.033

Abstract To date, miniaturization of fluid handling and fluid analysis devices in the medicine engineering has been emerging in the interdisciplinary research field of micro-fluidics, as a result of miniaturization of the detective device to allow parallelization as well as to reduce analysis time and sample volume. Micro-total-analysis-system (μ -TAS) researches aimed at developing miniaturized and integrated ``lab-on-a-chip'' devices for biochemical analysis applications. Droplet-based micro-mixer is the one of the key components in the developing of μ-TAS. Numerical approach on the dynamic formation of water droplets in a T-type microchannel with a 200μm × 50μm rectangular cross section and 1000μm long… More >

Qiang Li¹

CMES-Computer Modeling in Engineering & Sciences, Vol.94, No.3, pp. 207-224, 2013, DOI:10.32604/cmes.2013.094.207

Abstract In this paper, an immersed boundary method (IBM) has been developed to simulate three-dimensional (3D) complex flows in the injection molding process, in which the irregular boundary of mould is treated by a level set function. The melt front (melt-air interface) is captured and treated using the coupled level set and volume of fluid (CLSVOF) method. The finite volume method on the nonstaggered meshes is implemented to solve the governing equations, and the melt filling process is simulated in a rectangular mould with both thick- and thin-wall sections. The numerical result shows good agreement with the available data. Finally, the… More >