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 >

A. Podolny^1,2, A. Nepomnyashchy³, A. Oron⁴

FDMP-Fluid Dynamics & Materials Processing, Vol.6, No.1, pp. 13-40, 2010, DOI:10.3970/fdmp.2010.006.013

Abstract A general model for two-component transport phenomena applicable for both nanofluids and binary solutions is formulated. We investigate a combined long-wave Marangoni and Rayleigh instability of a quiescent state of a binary (nano-) liquid layer with a non-deformable free surface. The layer is heated from below or from above. The concentration gradient is induced due to the Soret effect. A typical behavior of monotonic and oscillatory instability boundaries is examined in the limit of asymptotically small Lewis numbers and poorly conducting boundaries in the two important long-wave domains k~Bi1/2and k~Bi1/4. 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 >

R. Prosser¹

FDMP-Fluid Dynamics & Materials Processing, Vol.5, No.4, pp. 411-424, 2009, DOI:10.3970/fdmp.2009.005.411

Abstract A novel wavelet-based method for the simulation of reacting flows on adaptive meshes is presented. The method is based on a subtraction algorithm, wherein the wavelet coefficients are calculated from the low resolution up (as opposed to the standard top-down approach). The advantage of this new method is that it allows the calculation of wavelet coefficients on sparse grids, and thus lends itself more readily to adaptive computational meshes than does the traditional wavelet algorithm. The approach is used to simulate a one-dimensional laminar pre-mixed flame with different Lewis numbers. The computational grid is adapted More >

A. B. Mahmud Hasan^1,2, S.M. Guo¹, M.A. Wahab¹

FDMP-Fluid Dynamics & Materials Processing, Vol.5, No.4, pp. 399-410, 2009, DOI:10.3970/fdmp.2009.005.399

Abstract The effects of gas flow channel design were studied experimentally for increasing fuel cell performance and fuel optimization. Three types of gas flow channels (serpentine, straight and interdigitated) were designed on the basis of water flooding due to electrochemical reactions, electro-osmotic drag, etc. Experimental results indicate that the best cell performance can be obtained by arranging interdigitated gas flow channel at the anode side and serpentine gas flow channel at the cathode side. Detailed analysis on complex two phase water generation and electrochemical phenomena behind those results were analyzed in this work to find out More >

A. K. Plappally^1,3, I. Yakub^2,3, L. C. Brown^1,2,3, A. B. O. Soboyejo¹

FDMP-Fluid Dynamics & Materials Processing, Vol.5, No.4, pp. 373-398, 2009, DOI:10.3970/fdmp.2009.005.373

Abstract Water flow through point-of-use porous ceramic water treatment filters have been theoretically analyzed in this technical paper. Filters tested were manufactured by combining low cost materials namely, clay and sawdust. Three filters with distinct volume fractions of clay to sawdust (75:25, 65:35 and 50:50) were tested. Sintered clay filters casted in frustum shapes were structurally characterized using mercury intrusion porosimetry. A linear increase in porosity with volume fraction of sawdust was observed. Flow experiments were carried out at constant room temperature and pressure. Potable tap water was used in these studies. Flows through filters occurring More >

A. Alke¹, D. Bothe¹

FDMP-Fluid Dynamics & Materials Processing, Vol.5, No.4, pp. 345-372, 2009, DOI:10.3970/fdmp.2009.005.345

Abstract We present a computational approach based on the Volume-of-Fluid (VOF) method for simulating the influence of a soluble surfactant on the behavior of two-phase systems with deformable interface. Our approach is applicable to diffusion controlled processes, where the relation between the area-specific excess surfactant concentration on the interface and the volume-specific concentration adjacent to the interface is given by an adsorption isotherm. Main issues of the numerical model are an extended surface transport theorem used for describing the interfacial flux and an iso-surface of the VOF-variable used as a connected approximation for the interface. 3D-simulations More >

N. Armour¹, S. Dost^1,2

FDMP-Fluid Dynamics & Materials Processing, Vol.5, No.4, pp. 331-344, 2009, DOI:10.3970/fdmp.2009.005.331

Abstract A combined numerical and experimental investigation has been undertaken to explore the benefits of an applied static magnetic field on Silicon transport into a Germanium melt. This work utilized a similar material configuration to that used in the Liquid Phase Diffusion (LPD) and Melt-Replenishment Czochralski (Cz) growth systems. The measured concentration profiles from the samples processed with and without the application of magnetic field showed very similar shape. The amount of silicon transport into the melt is slightly higher in the samples processed under magnetic field, and there is a substantial difference in dissolution interface… 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 >