Nedeltcho K,ev¹, Val Kagan², Ahmed Daoud¹

FDMP-Fluid Dynamics & Materials Processing, Vol.6, No.3, pp. 291-318, 2010, DOI:10.3970/fdmp.2010.006.291

Abstract Results are presented of 3D numerical magneto-hydrodynamic (MHD) simulation of electromagnetic DC pump for both laminar and turbulent metal flow under an externally imposed strongly non-uniform magnetic field. Numerous MHD flow cases were simulated using finite element method and the results of five typical examples are summarized here, including one example of laminar brake flow, one example of turbulent brake flow and three examples of turbulent pumping conditions. These simulations of laminar and turbulent channel flow of liquid metal correctly represent the formation of an M shaped velocity profile and are in good agreement with… More >

Shaligram Tiwari¹, Koichi Nishino²

FDMP-Fluid Dynamics & Materials Processing, Vol.6, No.1, pp. 109-136, 2010, DOI:10.3970/fdmp.2010.006.109

Abstract The present work reports about an experimental study investigating the influence of air convection and of ambient temperature around a half-floating zone on the transition behavior from steady to oscillatory flow, i.e. the influence on the critical Marangoni number (Macr). Increase of heat loss from the free surface of the half-floating zone or liquid bridge by increased convection and ambient cooling decreases Macr. Heat input to the free surface increases Macr. An add-on numerical simulation of the air convection around the zone clarifies the influence of air convection and the ambient temperature on the temperature, More >

I. Ueno¹, A. Kawazoe², H. Enomoto³

FDMP-Fluid Dynamics & Materials Processing, Vol.6, No.1, pp. 99-108, 2010, DOI:10.3970/fdmp.2010.006.099

Abstract The authors focus on thermocapillary-driven flow in a half-zone liquid bridge and its transition from two-dimensional steady flow to three-dimensional oscillatory one under an effect of forced convection in ambient gas region around the liquid bridge. The liquid bridge is settled in a cylindrical 'external shield,' in which upward/downward forced flow of the ambient gas is added. The critical condition of the flow transition in the 2-cSt silicone-oil liquid bridge is examined as functions of the aspect ratio and the volume ratio of the liquid bridge, and averaged velocity of the ambient gas. The authors More >

Yu. Gaponenko¹, I. Ryzhkov², V. Shevtsova³

FDMP-Fluid Dynamics & Materials Processing, Vol.6, No.1, pp. 75-98, 2010, DOI:10.3970/fdmp.2010.006.075

Abstract Gas-liquid flows in annulus are analyzed for fluids in large range of viscosity ratios. The geometry corresponds to a liquid bridge co-axially placed into an outer cylinder with solid walls. The internal core consists of solid rods at the bottom and top, while the central part is a relatively short liquid zone filled with viscous liquid and kept in its position by surface tension. The gas enters into the annular duct and entrains initially quiescent liquid. The flow structures in the liquid and gas are obtained numerically for different shapes of solid rods. Solution for More >

O.M.Lavrenteva, Yu. Holenbergand A.Nir¹

FDMP-Fluid Dynamics & Materials Processing, Vol.6, No.1, pp. 41-74, 2010, DOI:10.3970/fdmp.2010.006.041

Abstract A variety of exact analytical solutions describing natural and thermocapillary convection in a horizontal double layer system consisting of Newtonian and Herschel-Bulkley fluids subjected to longitudinal temperature and concentration gradients is constructed. The lower boundary of the system is a solid wall with no-slip, while the upper ones if either a solid wall or a free surface. It was demonstrated that, depending on the governing parameters of the system, viscoplastic layer is entirely yielded or unyielded, or it can be yielded partially, exhibiting up to 5 flowing and quasi-solid layers. The dependence of the flow More >

Rodica Borcia¹, Michael Bestehorn²

FDMP-Fluid Dynamics & Materials Processing, Vol.6, No.1, pp. 1-12, 2010, DOI:10.3970/fdmp.2010.006.001

Abstract We study numerically the fully nonlinear evolution of thin liquid films on solid supports in three spatial dimensions. A phase field model is used as mathematical tool. Homogeneous and inhomogeneous substrates are taken into account. For flat homogeneous substrates the stability of thin liquid layers is investigated under the action of gravity. The coarsening process at the solid boundary can be controlled on inhomogeneous substrates. On substrates chemically patterned in an adequate way with hydrophobic and hydrophilic spots (functional surfaces), one can obtain stable regular liquid droplets as final dewetted morphology. More >

F. Mechighel^1,2, M. El Ganaoui¹, M. Kadja², B. Pateyron³, S. Dost⁴

FDMP-Fluid Dynamics & Materials Processing, Vol.5, No.4, pp. 313-330, 2009, DOI:10.3970/fdmp.2009.005.313

Abstract A numerical study has been carried out to investigate the three-dimen -sional buoyant flow in a parallelepiped box heated from below and partially from the two sidewalls (a configuration commonly used for solidification problems and crystal growth systems). Attention has been paid, in particular, to phenomena of symmetry breaking and transition to unsteady non-symmetric convection for a low Prandtl number fluid (Pr=0.01). The influence of an applied horizontal magnetic field on the stability properties of the flow has been also considered. Results obtained may be summarized as follows: In the absence of magnetic field and More >

Davood Kalantari¹

FDMP-Fluid Dynamics & Materials Processing, Vol.5, No.1, pp. 81-92, 2009, DOI:10.3970/fdmp.2009.005.081

Abstract In this paper a theoretical approach is elaborated for modelling the impact and ensuing spreading behaviour of a liquid droplet after its collision with a flat and rigid surface. The major outcomes of such a study can be summarized as follows: 1) The propagating-shock-wave velocity associated with the droplet is not a constant value but depends on the impact velocity and the physical and geometrical properties of the droplet. 2) The initial radial ejection velocity of the lamella is proportional to the shock-wave velocity (ua) and the impact velocity (0) according to the expression (a-u0)1/2. More >

A.A. Ivanova¹, V.G. Kozlov^1,2,3, D.A. Polezhaev¹, D. Pareau³, M. Stambouli³

FDMP-Fluid Dynamics & Materials Processing, Vol.4, No.3, pp. 211-220, 2008, DOI:10.3970/fdmp.2008.004.211

Abstract The problem for the optimization of mass-transfer on the interface of two immiscible liquids by means of vibrational hydromechanics is studied experimentally. A new vibrational cell of Lewis's type expressly conceived for such purposes is described. Flow is generated by activators in the form of disks inducing translational axial oscillations near the opposite end faces of the cavity. It is shown that such vibrating disks can lead to the onset of a large-scale toroidal whirlwind effectively mixing the liquid throughout the volume. According to the experiments, in particular, axisymmetrical radial flows are generated on both More >

V. Shevtsova^1,2, A. Mialdun¹, C. Ferrera^1,4, M. Ermakov^3,4, J. M. Montanero⁴

FDMP-Fluid Dynamics & Materials Processing, Vol.4, No.1, pp. 43-54, 2008, DOI:10.3970/fdmp.2008.004.043

Abstract Dynamic free surface deformations induced by buoyant and thermocapillary convection in liquid bridges of 5cSt silicone oil are studied experimentally and numerically. The experiments are performed in ground conditions and static deformation is unavoidable. Convective motion starts in the liquid bridge as soon as ΔT ≠ 0 and initially leads to a stationary dynamic deformation of the free surface. Oscillatory motion starts at a critical value of ΔT and causes oscillations of the interface. The final supercritical shape of the free surface is a result of the static shape with superimposed subcritical stationary and oscillatory dynamic deformations. More >