THE INFLUENCE OF GRAVITY ON A MICROFLUIDIC MIXED CONVECTION BY APPLYING LATTICE BOLTZMANN METHOD

Abstract

In this article the effects of gravity on the mixed convection of a microflow is studied numerically by using lattice Boltzmann method (LBM). To do this, the hydrodynamic boundary condition equations should also be modified. The cold fluid enters to the microchannel and leaves it after cooling its hot walls. Calculations are provided for a wide range of Knudsen number (Kn). The results are presented as the isotherms and streamlines, the values of slip velocity and temperature jump and the local and global profiles of velocity, temperature and Nusselt number. It is observed that LBM is able to simulate the mixed convection in a microchannel appropriately. It is claimed that the effects of buoyancy forces are important for Kn0.05 they can be ignored. Moreover, the buoyancy forces make a rotational cell in the microchannel flow which generates the negative slip velocity at Kn=0.005