Heat Transfer in Porous Microchannels with Second-Order Slipping Boundary Conditions

Transport in Porous Media - The paper presents results of a study of forced convection in a vertical flat and circular microchannels incorporating porous medium under slip boundary conditions of...     

Numerical simulation of water jet breakup under the influence of flow velocity oscillations

Numerical investigations of forced water jet breakup under the influence of harmonic oscillations of the inlet velocity are carried out. An adequate model is used. Areas of jet breakup regimes under the influence of sinusoidal oscillations are determined.     

Convective Instability in Slip Flow in a Vertical Circular Porous Microchannel

The paper represents an analysis of convective instability in a vertical cylindrical porous microchannel performed using the Galerkin method. The dependence of the critical Rayleigh number on the Darcy, Knudsen, and Prandtl numbers, as well as on the ratio of the thermal conductivities of the fluid and the wall, was obtained. It was shown that a decrease in permeability of the porous medium (in other words, increase in its porosity) causes an increase in flow stability. This effect is substantially nonlinear. Under the condition Da?>?0.1, the effect of the porosity on the critical Rayleigh number practically vanishes. Strengthening of the slippage effects leads to an increase in the instability of the entire system. The slippage effect on the critical Rayleigh number is nonlinear. The level of nonlinearity depends on the Prandtl number. With an increase in the Prandtl number, the effect of slippage on the onset of convection weakens. With an increase in the ratio of the thermal conductivities of the fluid and the wall, the influence of the Prandtl number decreases. At high values of the Prandtl numbers (Pr?>?10), its influence practically vanishes.