C.T. Lee¹, C.C. Lee²

CMES-Computer Modeling in Engineering & Sciences, Vol.104, No.5, pp. 375-403, 2015, DOI:10.3970/cmes.2015.104.375

Abstract In this article, we demonstrate a numerical 3-D chip, and studied the capillary dynamics inside the microchannel. We applied the level set method on the Navier-Stokes equation which incorporates the surface tension and two-phase flow characteristics. We analyzed the capillary dynamics near the junction of two microchannels. Such a highlighting point is important that it not only can provide the information of interface behavior when fluids are made into a head-on collision, but also emphasize the idea for the design of the chip. In addition, we study the pressure distribution of the fluids at the More >

Ashraf Balabel¹,

CMES-Computer Modeling in Engineering & Sciences, Vol.89, No.4, pp. 283-301, 2012, DOI:10.3970/cmes.2012.089.283

Abstract This paper presents a novel numerical method for solving the twophase flow problems with moving interfaces in either laminar or turbulent flow regimes. The developed numerical method is based on the solution of the Reynolds- Averaged Navier Stokes equations in both phases separately with appropriate boundary conditions located at the interface separating the two fluids. The solution algorithm is performed on a regular and structured two-dimensional computational grid using the control volume approach. The complex shapes as well as the geometrical quantities of the interface are determined via the level set method. The numerical method More >

Yongsheng An¹, Xiaodong Wu¹, Deli Gao¹

CMES-Computer Modeling in Engineering & Sciences, Vol.89, No.2, pp. 123-142, 2012, DOI:10.3970/cmes.2012.089.123

Abstract The accuracy of numerical simulation of a two-phase (oil and water) flow in a fractured horizontal well depends greatly upon the types of grids used in the computation. Cartesian grids have been widely used in recent years, but they have some disadvantages in describing complex structural wells, such as fractured horizontal wells. For example, Cartesian grids are not efficient in describing the main wellbores and the fractures of fractured horizontal wells, and the results can frequently suffer from grid orientation effects, even though a grid-refinement is often introduced to enhance the adaptability of a Cartesian… More >

K. Ibrahim¹, W.A. El-Askary^1,2, A. Balabel¹, I.M. Sakr¹

CMES-Computer Modeling in Engineering & Sciences, Vol.85, No.1, pp. 79-104, 2012, DOI:10.3970/cmes.2012.085.079

Abstract In the present paper, a numerical code has been developed with different turbulence models aiming at simulating turbulent bubbly flows in vertical circular pipes. The mass and momentum conservation equations are used to describe the motion of both phases (water/air). Because of the averaging process additional models are needed for the inter-phase momentum transfer and turbulence quantities for closure. The continuous phase (water) turbulence is represented using different turbulence models namely: two-equation k-ε, extended k-ε and shear-stress transport (SST) k-ω turbulence models which contains additional term to account for the effect of the dispersed phase… More >

Ashraf Balabel

CMES-Computer Modeling in Engineering & Sciences, Vol.83, No.6, pp. 599-638, 2012, DOI:10.3970/cmes.2012.083.599

Abstract In the present paper, a new generalized level set numerical method based on the Fast Marching Method is developed for predicting the moving interface thermo-fluid dynamics in turbulent free surface flows. The numerical method is devoted to predict the turbulent interfacial dynamics resulting from either aerodynamic force or thermocapillary effects. The unsteady Reynolds averaged Navier-Stokes equations (RANS) and energy equation are coupled with the level set method and solved separately in each phase using the finite volume method on a non-staggered grid system. The application of the fast marching technique enables the fast as well… More >

N. Labed¹, L. Bennamoun², J.P. Fohr³

FDMP-Fluid Dynamics & Materials Processing, Vol.8, No.4, pp. 423-436, 2012, DOI:10.3970/fdmp.2012.008.423

Abstract Intrinsic and relative permeability are indispensable parameters for performing transfers in porous media. In this paper, the conception and ensuing exploitation of a new testing ground for measuring the relative permeability of water and nitrogen are presented. The experimental work was elaborated in the Laboratory of Thermal Studies in Poitiers, (France) where brick samples were used to verify the performance of the proposed testing strategy. The results prove the existence of several stages during the drainage and the imbibitions. In particular, the three stages observed for the case of gas permeability reduce to only two More >

H. Watanabe, M. Suzuki, N. Ito

The International Conference on Computational & Experimental Engineering and Sciences, Vol.18, No.2, pp. 49-50, 2011, DOI:10.3970/icces.2011.018.049

Abstract Gas-liquid two-phase flow is a system containing gas and liquid phase. While the gas-liquid two-phase flow is important for applications such as power plants and pump cavitations, it is difficult to study gas-liquid multiphase flow theoretically or numerically since it is multi-scale and multi-physics system involving not only flow but also phase transitions. In order to overcome the difficulties, we study the two-phase flow with full particle simulations. In the full-particle simulation, phase boundaries create and annihilate spontaneously, and therefore, multi-physics phenomena are naturally simulated. We developed a parallel molecular dynamics (MD) simulation code which More >

Qin Lou¹, Zhaoli Guo^1,2, Chuguang Zheng¹

CMES-Computer Modeling in Engineering & Sciences, Vol.76, No.3&4, pp. 175-188, 2011, DOI:10.3970/cmes.2011.076.175

Abstract Due to the mesoscopic and kinetic nature, the lattice Boltzmann equation (LBE) method has become an efficient and powerful tool for modeling and simulating interfacial dynamics of multi-phase flows. In this work we discuss several fundamental properties of two-phase LBE models. Particularly, the effects of force discretization, spurious currents in the vicinity of interfaces, and checkerboard effects with the underlying lattices, are investigated. More >

T. Uchiyama¹

FDMP-Fluid Dynamics & Materials Processing, Vol.7, No.4, pp. 371-388, 2011, DOI:10.3970/fdmp.2011.007.371

Abstract This study proposes a three-dimensional grid-free method to simulate particle-laden gas flows. It is based on a vortex method. The flow region is not resolved into computational grids, but the gas vorticity field is discretized by vortex elements. The behavior of the vortex element and the particle motion are simultaneously calculated by using the Lagrangian approach. Eight cubic cells are locally allocated around each particle to compute the effect of the particle motion on the gas flow. In each cell, the change in the vorticity due to the particle is calculated, and it is considered… More >

Chen Fang^*, Milnes David, Anita Rogacs, Kenneth Goodson

Frontiers in Heat and Mass Transfer, Vol.1, No.1, pp. 1-11, 2010, DOI:10.5098/hmt.v1.1.3002

Abstract Vapor-venting microchannel heat exchangers are promising because they address the problems of high pressure drop, flow instability, and local dryout that are common in conventional two-phase microchannel heat sinks. We present a 3D numerical simulation of the vapor-venting process in a rectangular microchannel bounded on one side by a hydrophobic porous membrane for phase-separation. The simulation is based on the volume of fluid (VOF) method together with models for interphase mass transfer and capillary force. Simulation shows the vapor-venting mechanism can effectively mitigate the vapor accumulation issue, reduce the pressure drop, and suppress the local More >