A. Filali¹, L. Khezzar^1,2

FDMP-Fluid Dynamics & Materials Processing, Vol.9, No.3, pp. 307-329, 2013, DOI:10.3970/fdmp.2013.009.307

Abstract Numerical investigations of purely-elastic instabilities occurring in creeping flows are reported in planar cross-slot geometries with both sharp and round corners. The fluid is described by the upper-convected Maxwell model, and the governing equations are solved using the finite element technique based on a steady (non-iterative) direct solver implemented in the POLYFLOWcommercial software (version 14.0). Specifically, extensive simulations were carried out on different meshes, with and without the use of flow perturbations, for a wide range of rheological parameters. Such simulations show the onset of flow asymmetries above a critical Deborah number (De). The effect More >

D. Srinivasacharya¹, G. Swamy Reddy¹

FDMP-Fluid Dynamics & Materials Processing, Vol.9, No.3, pp. 291-305, 2013, DOI:10.3970/fdmp.2013.009.291

Abstract Free convection and related heat and mass transfer along a vertical plate embedded in a power-law fluid saturated Darcy porous medium with thermal and solutal stratification effects is studied. The governing partial differential equations are transformed into ordinary differential equations using similarity transformations and then solved numerically by means of a shooting method. The variations of non-dimensional velocity, temperature and concentration are presented graphically for various values of the power-law index, and of the thermal and solutal stratification parameters. In addition, the heat and mass transfer rates are tabulated for different values of the governing More >

Lazhar Merouani¹, Belkacem Zeghmati², Azeddine Belhamri³

FDMP-Fluid Dynamics & Materials Processing, Vol.9, No.3, pp. 267-290, 2013, DOI:10.3970/fdmp.2013.009.267

Abstract The present work is a numerical study of laminar film condensation from vapor-gas mixtures in an inclined channel with an insulated upper wall and an isothermal lower wall coated with a thin porous material. A two-dimensional model is developed using a set of complete boundary layer equations for the liquid film and the steam-air mixture while the Darcy-Brinkman-Forchheimer approach is used for the porous material. The governing equations are discretized with an implicit finite difference scheme. The resulting systems of algebraic equations are numerically solved using Gauss and Thomas algorithms. The numerical results enable to More >

G. C. Rana¹, R. C. Thakur²

FDMP-Fluid Dynamics & Materials Processing, Vol.9, No.3, pp. 251-265, 2013, DOI:10.3970/fdmp.2013.009.251

Abstract In this paper, the effect of suspended particles on thermal convection in a compressible viscoelastic fluid hosted in a porous medium is considered. For the porous medium, the Brinkman model is employed with the Rivlin-Ericksen approach used in parallel to describe the rheological behaviour of the viscoelastic fluid. By applying a normal mode analysis method, a dispersion relation is derived and solved analytically. It is observed that the medium permeability, suspended particles, gravity field and viscoelasticity introduce oscillatory modes. For stationary convection, it is found that the Darcy-Brinkman number has a stabilizing effect whereas the More >

O. Mahrouche¹, M. Najam¹, M. El Alami^1,2, M. Faraji¹

FDMP-Fluid Dynamics & Materials Processing, Vol.9, No.3, pp. 235-250, 2013, DOI:10.3970/fdmp.2013.009.235

Abstract Mixed convection in a rectangular partitioned cavity equipped with two heated partitions at a constant temperature, T_C, is investigated numerically. The right vertical wall is featured by two openings (C₁ and C₂) for admission of cooled air along the horizontal direction, while the lower wall has a single outlet opening (C₃) along the vertical axis. The left vertical wall is assumed to be isothermal at temperature T_C, while the other walls are cooled to a temperature T_F < T_C. The results show that the flow and heat transfer depend significantly on Reynolds number, Re, and block height, B. Correlation More >

V. Haslavsky, E. Miroshnichenko, E. Kit, A. Yu. Gelfgat

FDMP-Fluid Dynamics & Materials Processing, Vol.9, No.3, pp. 209-234, 2013, DOI:10.3970/fdmp.2013.009.209

Abstract Experimental and numerical observations of oscillatory instability of melt flow in a Czochralski model are compared, and a disagreement observed at small crystal dummy rotation rates is addressed. To exclude uncertainties connected with flow along the free surface, the latter is covered by a no-slip thermally insulating ring. Experiments reveal an appearance of oscillations at temperature differences smaller than the numerically predicted critical ones. At the same time, a steep increase of the oscillations amplitude is observed just beyond the computed threshold values. By increasing the dummy rotation gradually, we are able to qualitatively confirm More >

A. Rtibi¹, M. Hasnaoui¹, A. Amahmid¹

FDMP-Fluid Dynamics & Materials Processing, Vol.9, No.2, pp. 183-207, 2013, DOI:10.3970/fdmp.2013.009.183

Abstract In this paper we present an analytical and numerical study of Soret convection in an inclined rectangular porous layer saturated with a binary fluid and subject to uniform heat fluxes. In the problem formulation, the Darcy model is considered and the results are presented for wide ranges of R_T (50 ≤ R_T ≤ 1000), θ(0°≤θ≤180°) and φ(-1 ≤ φ ≤ 1) for Le = 10, where R_T, θ, φ, and Le are the thermal Darcy-Rayleigh number, the cavity inclination, the separation parameter, and the Lewis number, respectively. An analytical solution, derived on the basis of the parallel flow approximation,… More >

Davood Kalantari¹

FDMP-Fluid Dynamics & Materials Processing, Vol.9, No.2, pp. 169-182, 2013, DOI:10.3970/fdmp.2013.009.169

Abstract In this study, a critical summary of existing spray/wall interaction models is given in synergy with a review of available experimental data. In particular, special attention is devoted to the limitations, difficulties and complexities of the most used approaches in the literatures. An attempt is also made to indicate the bottlenecks and criticalities which typically arise when investigators try to extend results obtained for isolated droplets to the more complex dynamics produced by spray impacts. More >

E. A. El-Abeedy¹, A. A. Busedra¹

FDMP-Fluid Dynamics & Materials Processing, Vol.9, No.2, pp. 153-167, 2013, DOI:10.3970/fdmp.2013.009.153

Abstract Fully developed laminar mixed convection in inclined semicircular ducts is investigated numerically for the specific case of uniform heat input along the axial direction and uniform peripheral wall temperature, H1. The duct is considered over a variety of orientations (rotations) of its cross section, ranging from 0° (flat wall horizontally facing upward) to 180° (flat wall horizontally facing downward) with increment of 45° and a fixed inclination of its axis (with respect to the direction of gravity). In particular, the following conditions are considered: inclination α = 20°, 300 ≤ Re ≤ 1000, Pr = 4 More >

D. Cherrared¹, E. G. Filali¹

FDMP-Fluid Dynamics & Materials Processing, Vol.9, No.2, pp. 127-151, 2013, DOI:10.3970/fdmp.2013.009.127

Abstract Our study deals with the characterization of the flow and related heat transfer in a smooth, circular minichannel. A duct with a sudden (sharp-edged) contraction is also considered. Prediction of the pressure loss coefficient in this case is obtained via the commercial code CFX 5.7.1. This code is based on the finite volume method for the solution of the Navier-Stokes and offers several turbulences models (in this study we use the shear stress turbulence model - SST). The numerical results are compared with experimental results obtained for a configuration similar to those considered in the More >