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  • Open Access

    ARTICLE

    Comparison and a Possible Source of Disagreement between Experimental and Numerical Results in a Czochralski Model

    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 >

  • Open Access

    ARTICLE

    Nonlinear Development of Interfacial Instability in a Thin Two-Layer Liquid Film in the Presence of Van-Der-Waals Interactions

    A. A. Nepomnyashchy1,2, I. B. Simanovskii1

    FDMP-Fluid Dynamics & Materials Processing, Vol.4, No.3, pp. 185-198, 2008, DOI:10.3970/fdmp.2008.004.185

    Abstract The development of instabilities under the joint action of the van der Waals forces and Marangoni stresses in a two-layer film on a heated or cooled substrate is considered. It is found that heating from below leads to the acceleration of the decomposition, decrease of the characteristic lateral size of structures, and the increase of the droplets heights. Heating from above leads to slowing down the instability rate and eventually to a complete suppression of the instability. More >

  • Open Access

    ARTICLE

    Electromagnetic Levitation Part I: Theoretical and Experimental Considerations

    Sayavur I. Bakhtiyarov1, Dennis A. Siginer2

    FDMP-Fluid Dynamics & Materials Processing, Vol.4, No.2, pp. 99-112, 2008, DOI:10.3970/fdmp.2008.004.099

    Abstract Levitation of liquid bodies against gravity is a contactless confinement process appropriate for manufacturing very pure materials. A variety of levitation techniques have been developed over the last few decades, such as aerodynamic, acoustic, electrostatic, microwave, and electromagnetic levitations. More recently, a new generation of novel techniques, essentially combinations of the established primary techniques, has been successfully introduced. Examples are acoustic-electric, aerodynamic-acoustic and acoustic-electromagnetic. The purpose of this series of papers in three parts, Bakhtiyarov and Siginer (2007a,b), is to review the advances in electromagnetic levitation (EML) since its introduction as a containerless melting technique, and a tool for the… More >

  • Open Access

    ARTICLE

    Effect of Large Eccentric Rotation on the Stability of Liquid Bridges

    A. Laverón-Simavilla1, V. Lapuerta1, J. Rodríguez1, M. A. González1

    FDMP-Fluid Dynamics & Materials Processing, Vol.3, No.4, pp. 339-348, 2007, DOI:10.3970/fdmp.2007.003.339

    Abstract A cylindrical liquid bridge supported between two circular-shaped disks in isorotation is considered. The effect of an offset between the rotation axis and the axis of the two supporting disks (eccentricity) on the stability of the liquid bridge is investigated. In a previous work a numerical method used to determine the stability limit for different values of eccentricity was validated comparing these results with analytical and experimental results for small eccentricity values, recovering the same behavior. In this work we use the numerical method to extend the analysis to large values of the eccentricity, finding a change in the bifurcation… More >

  • Open Access

    ARTICLE

    Axially Running Wave in Liquid Bridge

    D.E. Melnikov1, V.M. Shevtsova2

    FDMP-Fluid Dynamics & Materials Processing, Vol.3, No.4, pp. 329-338, 2007, DOI:10.3970/fdmp.2007.003.329

    Abstract Thermocapillary convection in a long vertical liquid column (called liquid bridge) subjected to heating from above is considered for a three-dimensional Boussinesq fluid. The problem is solved numerically via finite-volume method. Full system of three dimensional Navier-Stokes equations coupled with the energy equation is solved for an incompressible fluid. Instability sets in through a wave propagating in axial direction with zero azimuthal wave number, which is a unique stable solution over a wide range of supercritical heating. Further increasing the applied temperature difference results in bifurcation of a second wave traveling azimuthally with a slightly higher frequency. The two waves… More >

  • Open Access

    ARTICLE

    Instabilities and Pattern Formation in Thermocapillary Liquid Pools

    U. Schoisswohl1, H. C. Kuhlmann2

    FDMP-Fluid Dynamics & Materials Processing, Vol.3, No.4, pp. 317-328, 2007, DOI:10.3970/fdmp.2007.003.317

    Abstract The flow in thermocapillary liquid pools heated or cooled from above can exhibit various flow patterns depending on the thermal conditions and the geometrical constraints. This pattern formation and the respective physical mechanisms are studied numerically by means of a linear-stability analysis. We focus on the transition from the steady axisymmetric to a three-dimensional flow. More >

  • Open Access

    ARTICLE

    On the Stability of the Hadley Flow under the Action of an Acoustic Wave

    M.K. Achour1, S. Kaddeche2, A. Gharbi2, H. Ben Hadid3, D. Henry3

    FDMP-Fluid Dynamics & Materials Processing, Vol.1, No.4, pp. 277-284, 2005, DOI:10.3970/fdmp.2005.001.277

    Abstract The effects of an acoustic wave on the instabilities occurring in a lateral differentially heated cavity are investigated numerically. Linear stability results show that the acoustic wave affects significantly the instability characteristics of such a Hadley flow. Indeed, the sound field is found to stabilize both two dimensional transverse stationary and three dimensional longitudinal oscillatory instabilities which are the most critical modes affecting the buoyant convection in the fluid layer. Nevertheless, when stabilized by an acoustic wave, the 2D modes turn from stationary to oscillatory, with the known consequences of such a change on mass and heat transfer, especially in… More >

  • Open Access

    ARTICLE

    Numerical Simulation of CZ Crystal Growth of Oxide

    T. Tsukada1, M. Kobayashi2, C. J. Jing3, N. Imaishi4

    FDMP-Fluid Dynamics & Materials Processing, Vol.1, No.1, pp. 45-62, 2005, DOI:10.3970/fdmp.2005.001.045

    Abstract In this paper, our recent numerical studies on the Czochralski (CZ) crystal growth of oxide are surveyed. In the first part of the analysis, a "global" heat transfer model for an inductively heated CZ furnace is introduced and depicted in detail. It is emphasized that accounting for the internal radiation within the crystal and/or melt is of crucial importance since they are often semitransparent to infrared radiation. Results coming from such a "global" approach suggest that the melt/crystal interface shape is strongly affected by the optical properties of the crystal, of the melt and by the melt convection. The second… More >

  • Open Access

    ARTICLE

    On the Three-Dimensional Instability of Thermocapillary Convection in Arbitrarily Heated Floating Zones in Microgravity Environment

    A.Yu. Gelfgat1, A. Rubinov2, P.Z. Bar-Yoseph2, A. Solan2

    FDMP-Fluid Dynamics & Materials Processing, Vol.1, No.1, pp. 21-32, 2005, DOI:10.3970/fdmp.2005.001.021

    Abstract The three-dimensional instability of the thermocapillary convection in cylindrical undeformable floating zones heated laterally is studied numerically. Different types of the boundary conditions, including radiation heating, linearized radiation and prescribed heat flux are used in the calculation. Stability diagrams showing the Prandtl number dependence of the critical Marangoni numbers that represent the thermocapillary forcing for different heating conditions are reported. It is shown that the primary instability of initially axisymmetric thermocapillary flows is defined mainly by the total amount of heat supplied through the heated side surface. The way in which the heat is supplied has a less significant effect… More >

  • Open Access

    ARTICLE

    Elastic Instability of Pseudo-Elastic Rubber Balloons

    Ren Jiusheng1

    CMC-Computers, Materials & Continua, Vol.7, No.1, pp. 25-32, 2008, DOI:10.3970/cmc.2008.007.025

    Abstract Elastic instability for the inflation and deflation of a thin-walled spherical rubber balloon is examined within the framework of finite pseudo-elasticity. When a spherical rubber balloon is inflated, it is subject to a complex deformation after a pressure maximum has been obtained. One part of the balloon is lightly stretched while the remainder becomes highly stretched. So an aspherical deformation is observed after the initial spherical inflation. A pseudo-elastic strain energy function including a damage variable which may model the loading, unloading and reloading of rubber is used. The balloon is idealized as an elastic membrane and the inflation, deflation… More >

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