Non-isothermal slip flow over micro spherical particle at low Reynolds numbers

In present work, a numerical study was carried out to investigate the non-isothermal slip flow over a micro spherical particle at low Reynolds numbers. The slip boundary conditions (non-equilibrium momentum exchange and heat transfer) were adopted in the numerical model to predict the discontinuity phenomena at the gas-particle interface. It shows that the drag force acting on the particle and the average Nusselt number on the particle surface both decrease as the Knudsen number increases, which are caused by the effects of velocity slip and temperature jump on the gas-particle interface, respectively. As the particle temperature increases, the drag coefficient increases due to the increasing gas viscosity and the average Nusselt number decreases as the heat conduction becomes dominant at low Reynolds numbers. The influence of gas compressibility on the flow and heat transfer processes were studied based on the numerical predictions, which should be considered for the non-isothermal gaseous flow in the slip regime even if the Mach number is smaller than 0.3. And the effect of gas variable properties cannot be neglected as the temperature difference exists between the particle and gaseous fluid.