FEATURES OF HEAT TRANSFER IN A FLAT POROUS MICROCHANNEL WITH THE SECOND ORDER SLIP BOUNDARY CONDITIONS

The results of the study of heat transfer under forced convection in a flat porous microchannel taking into account the boundary conditions of slippage of the first and second order are considered. The simulation showed that with decreasing porosity the flow velocity in the central part of the microchannel and the slipping velocity on the wall decrease due to the increase in hydrodynamic resistance. Taking into account the influence of the boundary conditions of the second order shows that the magnitude of the velocity jump on the wall varies depending on the value of the parameter A2. The jump decreases with a positive value of A2, with a negative value - increases in comparison with the case A2 = 0 (first order boundary conditions). Qualitatively similar effects of porosity and second-order boundary conditions were also observed with respect to temperature profiles. The results of the calculation of the relative Nusselt number showed that the decrease in porosity contributes to the intensification of heat transfer. The dynamics of the change in the heat transfer coefficient with an increase in the Knudsen number indicates that an increase in the Prandtl number also leads to an improvement in the thermal interaction of the flow with the channel wall. The analysis of taking into account the boundary conditions of the second order showed that at small values of the Prandtl number (Pr ≤ 1) the influence of the parameter A2 was not observed. At A2 < 0 the effects of the boundary conditions of the second order lead to an increase in the relative Nusselt number, whereas at A2> 0 the value of the normalized Nusselt number decreases in comparison with the case A2 = 0 (boundary conditions of the first order).