Multi‐Scale Simulations of Gas Flows: Effect of External Forces

Multi‐scale simulations of neutral and charged particles in external fields require accurate algorithms for solving both the Boltzmann kinetic equation and continuum (Navier‐Stokes and Euler) equations. We develop direct methods of solving kinetic and fluid equations for multi‐scale simulations of rarefied and continuum gas flows in a wide range of Mach and Knudsen numbers. For the Boltzmann equation, we investigate adaptive mesh in velocity space and high‐order numerical schemes. For the continuum equations, we use kinetic schemes with accurate calculation of fluxes on cell faces using conservative implementation of the force term. We obtain correct gas behavior in external fields without parasite numerical heating. Coupled kinetic/hydrodynamic simulations of gas flows around rotating objects in moving reference frame are demonstrated.