Numerical study of the Couette flow of a diatomic rarefied gas

The Couette flow is numerically studied using a model kinetic equation for a diatomic rarefied gas (nitrogen). The boundary condition set on the wall takes into account that the molecular rotational energy passes into translational energy when the molecule interacts with the wall. For comparison purposes, the Couette flow is computed using the classical diffuse model of the gas-wall interaction. A comparison of the results obtained with both types of boundary conditions shows that the computed parameters of the Couette flow coincide only for sufficiently low Knudsen numbers. This suggests that transitions between rotational and translational energy in the gas-wall interaction have to be taken into account in the boundary condition.