Filtered Hyperbolic Moment Equations

Abstract: The Boltzmann equation can be used for numerical simulations of rarefied gases using

continuum models. Examples of continuum models beyond the validity of Euler or Navier-Stokes

equations are so-called moment models that extend the number of flow variables by additional

moments to account for non-equilibriumeffects. An accurate solution of the Boltzmann equation

by moment models requires a large number of those moments.

 

In this talk, I will give a brief introduction to moment models for the Boltzmann equation and then

present a filtered hyperbolic moment method that uses a filter for the higher order moment coefficients.

It can be shown that filtering is equivalent to an additional source term in the moment model. The

application of the filter leads to accelerated convergence of the moment model. I will show the

analogy to averaged solutions and motivate the use of filters and additional source terms along with

numerical results. The new method outperforms existing methods with respect to accuracy without

additional computational cost.