Mustapha Faraji¹, El Alami Mustapha, Najam Mostafa

FDMP-Fluid Dynamics & Materials Processing, Vol.10, No.2, pp. 279-298, 2014, DOI:10.3970/fdmp.2014.010.279

Abstract A study is reported of heat transfer and melting in a fan-less thermal management system consisting of an insulated horizontal cavity filled with a phase change material (PCM) and heated from below by a conducting plate supporting three identical protruding heat sources. Such a PCM enclosure can be used as a heat sink for the cooling of electronic components. The advantage of this cooling strategy is that PCMs characterized by high energy storage density and small transition temperature interval, are able to store a high amount of heat (thereby providing efficient passive cooling). A two-dimensional simulation model is developed that… More >

M. Si Abdallah¹, B. Zeghmati²

FDMP-Fluid Dynamics & Materials Processing, Vol.10, No.2, pp. 261-277, 2014, DOI:10.3970/fdmp.2014.010.261

Abstract In the present work, a numerical analysis is performed of the combined effects of (opposing) thermal and solutal buoyancy in the presence of a wavy (vertical) surface. The boundary layer equations and related boundary conditions are discretized using a finite volume scheme and solved numerically using a Gauss-Seidel algorithm. The influence of the wavy geometry (in terms of related wavelength L and amplitude a) and the buoyancy ratio N on the local Nusselt and Sherwood numbers and on the skin-friction coefficient are studied in detail. Results show that when Pr < Sc, negative values of the buoyancy parameter, N tend… More >

D. Benmouhoub¹, A. Mataoui¹

FDMP-Fluid Dynamics & Materials Processing, Vol.10, No.2, pp. 241-260, 2014, DOI:10.3970/fdmp.2014.010.241

Abstract The present work is devoted to the numerical study of the interaction of an inclined plane turbulent jet with a moving horizontal isothermal hot wall. The inclination of the jet allows the control of the stagnation point location. Numerical predictions based on statistical modeling are obtained using a second order Reynolds stress turbulence model coupled to an enhanced wall treatment. For a given impinging distance H (H =8e), the considered problem parameters are: (a) jet exit Reynolds number (Re, based on the thickness "e" of the nozzle) in the range from 10000 to 25000, (b) surface-to-jet velocity ratio Rsj from… More >

V. Shevtsova¹, Y. Gaponenko¹, H.C. Kuhlmann², M. Lappa³, M. Lukasser², S. Matsumoto⁴, A. Mialdun¹, J.M. Montanero⁵, K. Nishino⁶, I. Ueno⁷

FDMP-Fluid Dynamics & Materials Processing, Vol.10, No.2, pp. 197-240, 2014, DOI:10.3970/fdmp.2014.010.197

Abstract Pure surface-tension-driven flow is a unique type of flow that can be controlled through external manipulation of thermal and/or mechanical boundary conditions at the free liquid surface where the entire driving force for the convection is generated. This unique feature has been exploited in recent studies for the active control of the flow instability. The use of forced coaxial gas streams has been proposed as a way to stabilize the Marangoni convection in liquid bridges in the planned space experiment JEREMI (Japanese and European Research Experiment on Marangoni Instabilities). It is aimed at understanding the mechanism of the instability and… More >

Paras Ram^1,2, Vikas Kumar³

FDMP-Fluid Dynamics & Materials Processing, Vol.10, No.2, pp. 179-196, 2014, DOI:10.3970/fdmp.2014.010.179

Abstract The present study is carried out to examine the effects of temperature dependent variable viscosity on the three dimensional steady axi-symmetric Ferrohydrodynamic (FHD) boundary layer flow of an incompressible electrically nonconducting magnetic fluid in the presence of a rotating disk. The disk is subjected to an externally applied magnetic field and is maintained at a uniform temperature. The nonlinear coupled partial differential equations governing the boundary layer flow are non dimensionalized using similarity transformations and are reduced to a system of coupled ordinary differential equations. To study the effects of temperature dependent viscosity on velocity profiles and temperature distribution within… More >

J.R. Lin¹, L.M. Chu², T.L. Chou³, L.J. Liang³, P.Y. Wang³

FDMP-Fluid Dynamics & Materials Processing, Vol.10, No.2, pp. 163-177, 2014, DOI:10.3970/fdmp.2014.010.163

Abstract We investigate the influence of non-Newtonian micropolar fluids on the dynamic characteristics of wide tapered-land slider bearings. The study is carried out on the basis of the micro-continuum theory originally developed by Eringen (1966). Analytical expressions for the linear dynamic coefficients are provided and compared with earlier results in the literature. In particular, direct comparison with the Newtonian fluid-lubricated tapered-land bearings by Lin et al. (2006) indicates that the use of non-Newtonian micropolar fluids can lead to a significant increase in the values of stiffness and damping coefficients. Such improvements are found to be even more pronounced for larger values… More >

K. Lahmer¹, R. Bessaïh¹, A. Scipioni², M. El Ganaoui²

FDMP-Fluid Dynamics & Materials Processing, Vol.10, No.1, pp. 149-162, 2014, DOI:10.3970/fdmp.2014.010.149

Abstract This paper summarizes the outcomes of a numerical study about the phenomenon of hydrogen absorption in an axisymmetric tank geometry containing magnesium hydride heated to 300˚C and at moderate storage pressure 1 MPa. The governing equations are solved with a fully implicit finite volume numerical scheme (as implemented in the commercial software FLUENT). Different kinetic reaction equations modeling hydrogen absorption are considered and the related numerical simulations are compared with experimental results. Spatial and temporal profiles of temperature and concentration in hydride bed are plotted. More >

A. Abbassi^1,2, H. Ben Aissia¹

FDMP-Fluid Dynamics & Materials Processing, Vol.10, No.1, pp. 115-147, 2014, DOI:10.3970/fdmp.2014.010.115

Abstract This paper describes the transition from forced to mixed convection in a jet flow with variable properties. The classical laminar layer analysis is extended by taking into account the dependence of physical properties on temperature. The related model relies on the assumption that the variations of Prandtl number and specific heat at constant pressure are sufficiently small to be neglected. A second-order finite-difference numerical method based on a staggered grid is used to analyze transition, hydrodynamic and heat transfer phenomena in the jet. The dimensionless control parameter, Λ = T₀/T_∞, is limited to values less than 1. It is found… More >

Imen Mejri^1,2, Ahmed Mahmoudi¹, Mohamed Ammar Abbassi¹, Ahmed Omri¹

FDMP-Fluid Dynamics & Materials Processing, Vol.10, No.1, pp. 83-114, 2014, DOI:10.3970/fdmp.2014.010.083

Abstract This study examines natural convection in a square enclosure filled with a water-Al₂O₃ nanofluid and subjected to a magnetic field. The side walls of the cavity have spatially varying sinusoidal temperature distributions. The horizontal walls are adiabatic. A Lattice Boltzmann method (LBM) is applied to solve the governing equations for fluid velocity and temperature. The following parameters and related ranges are considered: Rayleigh number of the base fluid, from Ra=10³ to 10⁶, Hartmann number from Ha=0 to 90, phase deviation (γ =0, π/4, π/2, 3π/4 and π) and solid volume fraction of the nanoparticles between ø = 0 and 6%.… More >

Yan Shen¹, Hong Zhang^1,2,3, Hui Xu¹, Tong Bai¹, Ping Yu¹

FDMP-Fluid Dynamics & Materials Processing, Vol.10, No.1, pp. 63-81, 2014, DOI:10.3970/fdmp.2014.010.063

Abstract Single-unit and multi-unit models of porous media (metal felts) have been used to investigate thermal fluid-structure interaction phenomena in a liquid sodium system. Micro-scale aspects have been studied via numerical simulations. The permeability of metal felts has been measured experimentally to verify the reliability of the models used. This integrated approach has allowed a proper evaluation of the interdependencies among phenomena on different scales (including relevant information on skeleton deformation and pressure drop as a function of different parameters). Pressure drop generally increases with velocity and heat flux for both laminar and turbulent flows. The final deformation is greater when… More >