Local discrete velocity grids for deterministic rarefied flow simulations
This work addresses the computational expense of simulating high-speed rarefied gas flows for researchers in computational fluid dynamics.
The paper proposes using local, dynamically adapting velocity grids for deterministic rarefied flow simulations to reduce computational cost compared to global grids, demonstrating advantages and drawbacks in 1D test cases.
Most of numerical methods for deterministic simulations of rarefied gas flows use the discrete velocity (or discrete ordinate) approximation. In this approach, the kinetic equation is approximated with a global velocity grid. The grid must be large and fine enough to capture all the distribution functions, which is very expensive for high speed flows (like in hypersonic aerodynamics). In this article, we propose to use instead different velocity grids that are local in time and space: these grids dynamically adapt to the width of the distribution functions. The advantages and drawbacks of the method are illustrated in several 1D test cases.