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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 the numerically predicted flow destabilization.… More >

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1077

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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 laws… More >

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972

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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 suspended particles and medium permeability… More >

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1042

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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 determine the velocity, temperature and… More >

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1209

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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 nondimensional numbers. More >

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1122

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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 of rounding the corners is… More >

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