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 More >

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 More >

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 >

A. Pereira¹, P.M.J. Trevelyan², U. Thiele³, S. Kalliadasis¹

FDMP-Fluid Dynamics & Materials Processing, Vol.3, No.4, pp. 303-316, 2007, DOI:10.3970/fdmp.2007.003.303

Abstract We investigate the interaction between thin films and chemical reactions by using two prototype systems: a thin liquid film falling down a planar inclined substrate in the presence of an exothermic chemical reaction and a horizontal thin liquid film with a reactive mixture of insoluble surfactants on its surface. In the first case the chemical reaction has a stabilizing influence on the dynamics of the film and dampens the free-surface solitary pulses. In the second case the chemical reaction can destabilize the film and lead to the formation of free-surface solitary pulses. More >

M. Hennenberg¹, B. Weyssow², S. Slavtchev³, B. Scheid⁴

FDMP-Fluid Dynamics & Materials Processing, Vol.3, No.4, pp. 295-302, 2007, DOI:10.3970/fdmp.2007.003.295

Abstract A horizontal thin layer of ferrofluid is bordered by a solid and open to an inert gas on the other side. It is submitted to a heat gradient and a weak magnetic field, both being normal to the free deformable surface, leading to a coupling between the Marangoni phenomenon, induced by the variation of surface tension along the free deformable surface and the isothermal Cowley-Rosensweig problem, consequence of the magnetic field. The study of the steady compatibility condition shows a new pattern of stationary instability. The critical wavenumber is of O(√Bo), the Bond number Bo being More >

Rodica Borcia^1,2, Michael Bestehorn²

FDMP-Fluid Dynamics & Materials Processing, Vol.3, No.4, pp. 287-294, 2007, DOI:10.3970/fdmp.2007.003.287

Abstract We developed a phase field model for Marangoni convection in compressible fluids of van der Waals type far from criticality. The theoretical description is based on the Navier-Stokes equation with extra terms responsible for describing the Marangoni effect, the classical heat equation, and the continuity equation. The model previously developed for a two-layer geometry is now extended to drops and bubbles. Finally, we report on 2D numerical simulations for drop Marangoni migration in a vertical temperature gradient. More >

Srikrishna Sahu¹, K. Muralidhar¹, P.K. Panigrahi¹

FDMP-Fluid Dynamics & Materials Processing, Vol.3, No.3, pp. 265-286, 2007, DOI:10.3970/fdmp.2007.003.265

Abstract Convection in a differentially heated cavity partly filled with silicone oil has been experimentally studied. The air-oil layers are subjected to a temperature difference in the vertical direction, with the lower wall being heated with respect to the top. The overall geometry is that of an enclosed cavity that is octagonal in plan. Heights of oil layers considered for experiments correspond to 30, 50, and 70% of the vertical cavity dimension. Measurements have been carried out using a shadowgraph technique. A limited number of interferograms have also been recorded. The shadowgraph technique has been validated… More >

Joseph G. Lawrence, John P. Dismukes, Arunan Nadarajah¹

FDMP-Fluid Dynamics & Materials Processing, Vol.3, No.3, pp. 255-264, 2007, DOI:10.3970/fdmp.2007.003.255

Abstract The atmospheric chemical vapor deposition process on continuous glass sheets is a well developed one and the parameters that affect it are relatively well understood. When this process is converted to coat discrete glass plates it introduces a new variable, the gap between the glass plates, which can significantly impact the quality of the coatings. In this study a 2D pseudo steady state model of the process was developed to study the effect of the gap, and the ratio of outlet to inlet gas flow rates (called the bias), on the coating quality. The model… More >

Joseph G. Lawrence, Arunan Nadarajah¹

FDMP-Fluid Dynamics & Materials Processing, Vol.3, No.3, pp. 247-254, 2007, DOI:10.3970/fdmp.2007.003.247

Abstract A simplified 2D pseudo steady state model was developed for an atmospheric chemical vapor deposition (CVD) process on glass. This is used to study the feasibility of converting a continuous coating process to one with discrete glass plates with a gap between them. A preliminary estimate employing mass transfer correlations suggested that there would be significant concentration variations due to the gap between the plates. More detailed studies were done by solving the model numerically employing a finite difference scheme with a vorticity-stream function formulation, and employing the commercial computational fluid dynamics program FIDAP which… More >

Y. Yan¹, K. Jules², M. Z. Saghir¹

FDMP-Fluid Dynamics & Materials Processing, Vol.3, No.3, pp. 231-246, 2007, DOI:10.3970/fdmp.2007.003.231

Abstract Fluid science research including thermal diffusion in fluids benefits from the quiescent low-gravity environment provided by the International Space Station (ISS). However, residual gravities (or g-jitters) aboard the ISS impact the overall environment in which experiments are being performed. The impact of these residual gravities needs to be assessed to ensure that they are appropriately accounted for when results are being reported for experiments performed onboard the ISS. In this paper we study the thermal diffusion process in a ternary mixture of n-butane, dodecane and methane. Measured data from the Space Acceleration Measurement System (SAMS)… More >