Spectral method for the Boltzmann equation for gases with viscosity

We propose in this paper a spectral method for the Boltzmann equation for gases with viscosity/friction. We describe the density of particles and compare the results in the case of gases with friction and rarefied gas. This is the first numerical result for the equation. We show numerically that under the presence of the viscosity, the solution dissipates to 0. The larger the viscosity is, the faster the solution converges to 0.