On the importance of thermal creep in natural convective gas microflow with wall heat fluxes

Thermal creep occurs in gas microflow with wall heat fluxes. In this study, we investigate the creep effect on the steady natural convection in an open-ended vertical parallel-plate microchannel with asymmetric wall heat fluxes. The fully developed solutions for the velocity, pressure, temperature, flow rate, flow drag and heat transfer rate are derived analytically and presented for air at the standard reference state with complete accommodation. It is found that thermal creep has a significant effect. The effect is to unify the velocity and pressure and to elevate the temperature. Moreover, it tends to enhance the flow rate and heat transfer rate and to reduce the maximum gas temperature and flow drag. Its logarithm can be magnified by the decrease in the channel length and the increase in the Knudsen number.