Open Access

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L. Bennamoun¹, A. Belhamri²
FDMP-Fluid Dynamics & Materials Processing, Vol.4, No.4, pp. 221-230, 2008, DOI:10.3970/fdmp.2008.004.221
Abstract This work focuses on tyipical heat and mass transfer phenomena during the processing of products in the context of the packed-bed drying method (products arranged in thick layers into dryers working in forced convection mode). The dryers are modeled as porous media at the macroscopic level. The simulations are carried out using the mass, momentum (written in the framework of the Darcy's law approximation) and energy equations applied for the different components. A diffusion model based on Fick's law is also used to take into account the drying kinetics. This approach allows monitoring of the variations of humidity and temperature… More >

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881

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ARTICLE

Munther Issa K,ah¹, Jean-Luc Meunier²
FDMP-Fluid Dynamics & Materials Processing, Vol.4, No.4, pp. 231-236, 2008, DOI:10.3970/fdmp.2008.004.231
Abstract Multi-walled carbon nanotubes (MWCNTs) have been produced by chemical vapor deposition using acetylene as a hydrocarbon source at 700 \textdegree C. The Monel substrates coated with MWCNTs can be used later as cathodes in the Physical Vapor Deposition (PVD) systems to produce CNTs embedded in diamond-like carbon (DLC) film. This new method of generating MWCNTs on Monel substrates without using any catalyst is very simple and uses very little power compared to other CNTs generating techniques. Embedded CNTs in a crystalline carbon coat was observed on mirror-like polished Monel substrates at 700 \textdegree C but not on the rough Monel… More >

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890

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ARTICLE

R. Henda¹, W. Quesnel², Z. Saghir³
FDMP-Fluid Dynamics & Materials Processing, Vol.4, No.4, pp. 237-244, 2008, DOI:10.3970/fdmp.2008.004.237
Abstract The transient thermal behavior of a two-dimensional circulating porous bed is analytically investigated. A one-energy equation model, representing both the gas and solid phases via a unified temperature, is employed to describe the thermal behavior of the circulating bed. The latter is essentially a tube and shell heat exchanger commonly used in technologically important applications. The model equation is transformed into a simpler set of partial differential equations using an analytical procedure. The analytical solution, based on the method of separation of variables and the principle of superposition, is formulated for the calculation of the temperature distribution in the radial… More >

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766

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R. Abdeljabar¹, F. Onofri², M.J. Safi¹
FDMP-Fluid Dynamics & Materials Processing, Vol.4, No.4, pp. 245-254, 2008, DOI:10.3970/fdmp.2008.004.245
Abstract This paper focuses on the mechanisms of convective instability in a stable salty gradient layer (i.e. an interfacial salty layer). This layer is assumed to be initially confined between two homogeneous liquid layers: a lower layer composed of salty water of 5wt% concentration and an upper layer composed of distilled water. The mechanisms underlying the interfacial salty layer's instability are depicted experimentally using a PIV technique and via measurements of concentration and temperature. It is found that in addition to the effect of double-diffusion across the interfacial salty layer, different forms of Kelvin-Helmholtz instability occur at different locations:\newline i. At… More >

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756

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A. M. Ben-Arous¹, A. A. Busedra¹
FDMP-Fluid Dynamics & Materials Processing, Vol.4, No.4, pp. 255-262, 2008, DOI:10.3970/fdmp.2008.004.255
Abstract The problem of combined free and forced convection in horizontal semicircular ducts (flat wall at the bottom) with radial internal fins is investigated from a numerical point of view. The wall of the duct is assumed to have a uniform heat input along the axial direction with a uniform peripheral wall temperature (H1). The analysis focuses on the case of hydrodynamically and thermally fully-developed laminar flow. The governing equations for the velocity and temperature are solved by using a control-volume-based finite-difference approach. The fluid flow and heat transfer characteristics are found to be dependent on the Grashof number, the fin… More >

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819

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G. Accary¹, S. Meradji², D. Morvan², D. Fougère²
FDMP-Fluid Dynamics & Materials Processing, Vol.4, No.4, pp. 263-270, 2008, DOI:10.3970/fdmp.2008.004.263
Abstract In the literature, only few references have dealt with mixed-convection flows in the low Mach number approximation. For this reason, in the present study we propose to extend the standard 3D benchmark for mixed convection in a rectangular channel heated from below (Medale and Nicolas, 2005) to the case of large temperature variations (for which the Boussinesq approximation is no longer valid). The Navier-Stokes equations, obtained under the assumption of a low Mach number flow, are solved using a finite volume method. The results, corresponding to the steady-state case of the benchmark, lead to the idea of launching a call… More >

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767