DSMC investigation of rarefied gas flow in a four-sided lid driven cavity: Effect of rarefaction and lid velocities

Numerical Modelling of Hypersonic Flow of Spacecrafts

“…However, it is known that solving the Boltzmann equation directly is very difficult and time consuming due to its complexity of the collision integral term. An alternative approach to solve the Boltzmann equation is the particle-based Direct Simulation Monte Carlo method, which tracks a large number of particles and their collisions are described in a stochastic way [4]. This method is widely used for the investigation of rarefied flows.…”

“…This method is widely used for the investigation of rarefied flows. However, as the number of molecules increases, this method starts to have unacceptable memory demands near continuum regimes, especially caused by large number of collisions [2,4]. To estimate whether interactions on the molecular scale will affect transport of momentum and energy on the continuum scale, it is possible to calculate the ratio of the molecular mean free path to the characteristic length scale of the system.…”

“…Well known Navier-Stokes equations are only focused on the description of a continuum flow and they show limitations in capturing nonequilibrium conditions in rarefied gas flows. There have been few attempts to increase the applicability of Navier-Stokes equations, namely implementing the effects of self-diffusion [6] and adjusting velocity boundary conditions to include the slip flow [4]. There have been attempts to provide unified models, which could be able to describe all flow regimes (Fokker-Planck [7] or Hybrid methods [8]).…”