B. Madani¹, F. Topin², L. Tadrist²

FDMP-Fluid Dynamics & Materials Processing, Vol.6, No.4, pp. 351-368, 2010, DOI:10.3970/fdmp.2010.006.351

Abstract The present work deals with the hydraulic characterization of two-phase flow with phase change in a channel filled with metallic foam. We provide a general presentation of metallic foams including morphological characteristics, fabrication processes and industrial applications. The experimental facility, which consists of a hydrodynamic loop, the test section, measurement devices, and the data acquisition system, is presented. The Metallic foam sample tested in the present work is manufactured by SCPS (French manufacturer). N-pentane is used as a coolant fluid. The mass velocity values lie between 4 and 49 kg/ m2s, while the heating power in the test section ranges… More >

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 >

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 >

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 numerical study. The numerical algorithm… More >

Rashed Al-Ajmi¹, Mohamed Mosaad^1,2

FDMP-Fluid Dynamics & Materials Processing, Vol.8, No.1, pp. 51-68, 2012, DOI:10.3970/fdmp.2011.008.051

Abstract Conjugate heat transfer across a vertical solid wall separating natural convection in a cold fluid-saturated porous medium and film condensation in a saturated-vapour medium is analyzed. The analysis reveals that this thermal interaction process is mainly controlled by the thermal resistance ratio of wall to porous-side natural convection and that of condensate film to natural convection. Asymptotic and numerical results of interest are obtained for the local and mean overall Nusselt number as functions of these two thermal resistance ratios. More >

M. Mosaad², A. Ben-Nakhi², M. H. Al-Hajeri²

FDMP-Fluid Dynamics & Materials Processing, Vol.1, No.4, pp. 301-314, 2005, DOI:10.3970/fdmp.2005.001.301

Abstract This work deals with the problem of thermal interaction between two fluid media at two different bulk temperatures and separated by a vertical plate. The problem is analyzed by taking into account the heat conduction across the separating plate. The flow configuration considered is one in which the two vertical boundary layers of free and forced convection developed on plate sides are in parallel flow. The dimensionless parameters governing the thermal interaction mechanisms are analytically deduced. The obtained results are presented in graphs to demonstrate the heat transfer characteristics of investigated phenomenon. The work reports a means to estimate the… More >

Marcello Lappa¹

FDMP-Fluid Dynamics & Materials Processing, Vol.1, No.2, pp. 171-188, 2005, DOI:10.3970/fdmp.2005.001.171

Abstract The paper presents a comparative and critical analysis of some theoretical/experimental/numerical arguments concerning the possible stabilization of the surface-tension-driven (Marangoni) flow in the Floating Zone technique and in various related fluid-dynamic models. It is conceived as a natural extension of the focused overview published in Cryst. Res. Tech. 40(6), 531, (2005) where much room was devoted to discuss the intrinsic physical mechanisms responsible for three-dimensional and oscillatory flows in a variety of technological processes. Here, a significant effort is provided to illustrate the genesis of possible control strategies (many of which are still in a very embryonic condition), the underlying… More >

Marcello Lappa^{1, 2}

FDMP-Fluid Dynamics & Materials Processing, Vol.1, No.1, pp. 1-20, 2005, DOI:10.3970/fdmp.2005.001.001

Abstract Possible natural transport mechanisms in cubical and shallow cavities with different heating conditions (from below or from the side) are investigated by means of numerical solution of the non-linear model equations and multiprocessor computations. Attention is focused on a variety of three-dimensional steady effects that can arise in such configurations in the case of low-Pr liquids (silicon melt) even for relatively small values of the temperature gradient due to localized boundary effects and/or true instabilities of the flow. Such aspects are still poorly known or completely ignored owing to the fact that most of the existing experiments focused on the… More >

Chein-Shan Liu^1,2

CMC-Computers, Materials & Continua, Vol.5, No.1, pp. 31-42, 2007, DOI:10.3970/cmc.2007.005.031

Abstract By using a meshless regularized integral equation method (MRIEM), the solution of elastic torsion problem of a uniform bar with arbitrary cross-section is presented by the first kind Fredholm integral equation on an artificial circle, which just encloses the bar's cross-section. The termwise separable property of kernel function allows us to obtain the semi-analytical solutions of conjugate warping function and shear stresses. A criterion is used to select the regularized parameter according to the minimum principle of Laplace equation. Numerical examples show the effectiveness of the new method in providing very accurate numerical solutions as compared with the exact ones. More >

Thanh Q. Nguyen^1,2, Thao T. D. Nguyen³, H. Nguyen-Xuan^4,5,*, Nhi K. Ngo^1,2

CMC-Computers, Materials & Continua, Vol.61, No.1, pp. 27-53, 2019, DOI:10.32604/cmc.2019.07756

Abstract This paper presents a new approach using correlation and cross-correlation coefficients to evaluate the stiffness degradation of beams under moving load. The theoretical study of identifying defects by vibration methods showed that the traditional methods derived from the vibration measurement data have not met the needs of the actual issues. We show that the correlation coefficients allow us to evaluate the degree and the effectiveness of the defects on beams. At the same time, the cross-correlation model is the basis for determining the relative position of defects. The results of this study are experimentally conducted to confirm the relationship between… More >