J. Roszmann¹, Y.C. Liu¹, S. Dost^1,2, B. Lent¹, S. Grenier³, N. Audet³

FDMP-Fluid Dynamics & Materials Processing, Vol.5, No.3, pp. 231-244, 2009, DOI:10.3970/fdmp.2009.005.231

Abstract The article presents the results of a combined numerical and experimental study of the effect of rotating magnetic field on impurity transport in a zone refining system. An impurity (selenium) with a segregation coefficient close to unity was targeted. The three-zone system previously developed was used for experiments and numerical simulations. The numerical simulations were performed for tellurium (Te) and cadmium (Cd) molten zones, but the experiments could only be carried out for the Te-system. More >

M.M. Shemirani¹, M.Z. Saghir²

FDMP-Fluid Dynamics & Materials Processing, Vol.5, No.3, pp. 211-230, 2009, DOI:10.3970/fdmp.2009.005.211

Abstract A three-dimensional numerical modeling of Ge0.98Si0.02crystal growth is conducted to investigate the effect of g-jitter along with rotating magnetic field on the heat and mass transfer in the solvent region. It was found that the speed in the flow under the low frequency g-jitter is in the nano-centimeter per second and is too weak to have any impact on the silicon concentration in the process of crystallization near the growth interface. Different magnetic field intensities for different rotational speeds were examined. It was also found that rotating magnetic field not only did not suppress the convection but also generated an… More >

J.R. Lin¹, P.J. Li², T.C. Hung³

FDMP-Fluid Dynamics & Materials Processing, Vol.9, No.4, pp. 419-434, 2013, DOI:10.3970/fdmp.2013.009.419

Abstract On the basis of the Shliomis ferrofluid model (1972) together with the micro-continuum theory of Stokes (1966), the influences of non-Newtonian ferrofluids on the steady-state performance of long journal bearings have been investigated in the present paper. Analytical solutions for bearing performances are obtained from the non-Newtonian ferrofluid Reynolds-type equation. Comparing with the Newtonian non-ferrofluid case, the effects of non-Newtonian ferrofluids with applied magnetic fields provide an increase in the zero pressure-gradient angle and the load capacity, and a decrease in the friction parameter, especially for a larger non-Newtonian couple stress parameter and magnetic Langevin’s parameter. For the long journal… More >

E. Gedik¹, H.Kurt², Z.Recebli¹

FDMP-Fluid Dynamics & Materials Processing, Vol.9, No.1, pp. 23-33, 2013, DOI:10.3970/fdmp.2013.009.023

Abstract In this paper, the steady, laminar, incompressible viscous flow of an electrically conducting liquid-metal fluid is investigated numerically in a circular non-conducting pipe. The considered work fluid is Galinstan (GaInSn, i.e. Gallium-Indium-Tin). Such a liquid metal is subjected to a constant pressure gradient along the axial direction and a uniform transverse magnetic field in the spanwise direction. Numerical simulations are performed by means of the Fluent commercial software (used to solve the governing three dimensional fluid dynamics and electromagnetic field partial differential equations iteratively). The magnetic field induction, B, takes values between 0 and 1.5 T with a 0.5 T… More >

Evgeny V. Votyakov¹, Egbert A. Zienicke¹

FDMP-Fluid Dynamics & Materials Processing, Vol.3, No.2, pp. 97-114, 2007, DOI:10.3970/fdmp.2007.003.097

Abstract We simulated numerically the laminar flow in the geometry and the magnetic field of the experimental channel used in [Andreev, Kolesnikov, and Thess (2006)]. This provides detailed information about the electric potential distribution for the laminar regime (numerical simulation) and in the turbulent regime as well (experiment). As follows from comparison of simulated and experimental results, the flow under the magnet is determined by the interaction parameter N = Ha² / Re representing the ratio between magnetic force, determined by the Hartmann number Ha, and inertial force, determined by the Reynolds number Re. We compared two variants: (i)(Re,N)=(2000,18.6) (experiment), (400,20.25)… 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 >

N.I. Wakayama¹, D.C. Yin², J.W. Qi³

FDMP-Fluid Dynamics & Materials Processing, Vol.1, No.2, pp. 153-170, 2005, DOI:10.3970/fdmp.2005.001.153

Abstract The production of crystals of adequate size and high quality is the "bottleneck'' for three-dimensional structure analysis of protein crystals. In this work, in order to shed additional light on the (still controversial) beneficial effect of microgravity on crystal growth, we focus on recent advanced experimental and theoretical research about the effects of buoyancy-driven convection on protein crystallization. In the light of the numerical studies the following major outcomes can be highlighted: (1) when the crystal size exceeds several dozens of µm, buoyancy-driven convection dominates solute transport near the growing crystal and the crystal growth rate becomes larger than that… More >

C. W. Lan¹, B. C. Yeh

FDMP-Fluid Dynamics & Materials Processing, Vol.1, No.1, pp. 33-44, 2005, DOI:10.3970/fdmp.2005.001.033

Abstract The suppression of unstable Marangoni convection in floating-zone crystal growth by magnetic fields has enjoyed over recent years a widespread use as a reliable and useful strategy. A transversal direction of the field is particularly efficient, but asymmetric zone shapes and thus segregation are induced. Counter-rotation of the feed and of the crystal rods is a common way to improve dopant homogeneity. However, its effects under magnetic fields are complex and have not yet been studied in detail. In the present analysis, three-dimensional (3D) simulations based on a finite-volume/multigrid method are used to illustrate the effects of rotation on the… More >

SamiaM.Said¹

CMC-Computers, Materials & Continua, Vol.52, No.1, pp. 1-24, 2016, DOI:10.3970/cmc.2016.052.001

Abstract The present paper is concerned with the wave propagation in a micropolar thermoelastic solid with distinct two temperatures under the effect of the magnetic field in the presence of the gravity field and an internal heat source. The formulation of the problem is applied in the context of the three-phase-lag model and Green-Naghdi theory without dissipation. The medium is a homogeneous isotropic thermoelastic in the half-space. The exact expressions of the considered variables are obtained by using normal mode analysis. Comparisons are made with the results in the two theories in the absence and presence of the magnetic field as… More >

A.M. Farhan^{1, 2}

CMC-Computers, Materials & Continua, Vol.53, No.2, pp. 129-156, 2017, DOI:10.3970/cmc.2017.053.133

Abstract Employing Biot’s theory of wave propagation in liquid saturated porous media, the effect of rotation and magnetic field on wave propagation in a hollow poroelastic circular of infinite extent are investigated. An exact closed form solution is presented. General frequency equations for propagation of poroelastic cylinder are obtained when the boundaries are stress free. The frequencies are calculated for poroelastic cylinder for different values of magnetic field and rotation. Numerical results are given and illustrated graphically. The results indicate that the effect of rotation, and magnetic field are very pronounced. Such a model would be useful in large-scale parametric studies… More >