Investigation of Fluid Flow and Heat Transfer Characteristics of Gases in Microchannels with Consideration of Different Roughness Shapes at Slip Flow Regime

In this article, the effect of roughness shape on heat transfer and friction factor in microchannel flows is studied by numerical simulation of fluid flow and heat transfer in microchannels applying slip and temperature jump boundary conditions. The roughness is directly simulated with microelements of different shapes. Triangular peaks with periodic and random distributions are used to demonstrate the effect of roughness shape and distribution on Poiseuille and Nusselt numbers. Also, pressure gradients and surface heat fluxes are used to analyze the important parameters of fluid flow and heat transfer. Furthermore, rectangular and trapezoidal roughness elements have been used to compare the results with recently reported studies. Considering the fact that triangular roughness is a better model for the true geometry in a channel, it is found that changes in roughness shapes from triangular to rectangular or trapezoidal elements have a considerable effect on fluid flow and heat transfer characteristics. Results of this investigation show that Nusselt number is more sensitive to the roughness density than the roughness shape.