Accelerated Monte Carlo Methods for Rarefied Gas Dynamics

Monte Carlo simulations of rarefied gas dynamics are important for many applications. This project aims to substantially accelerate Monte Carlo (MC) algorithms and develop a rigorous and efficient computer code applicable for a wide range of Knudsen numberfrom rarefied to continuum flow regimes. This will be achieved by using implicit treatment of the collision processes, majorant frequency schemes based on master kinetic equation (MKE), and hybrid approaches combining continuum and kinetic descriptions ofthe flow. New MC schemes will provide accurate solutions with time steps much larger than required by standard DSMC, and ensure that for small Knudsen number the MC solution relaxes to local Maxwellian with conservation of mass, momentum and energy. HybridMC schemes and kinetic schemes of gas dynamics will be used to facilitate the automatic domain decomposition and coupling of the MC solution and continuum equations. The ultimate goal of the project is to develop a unified computer code that willautomatically switch between kinetic and continuum models to maximize computational efficiency and ensure numerical stability. The advantages of new methodologies will be demonstrated by comparison against traditional methods. The computational tool thatresults from this work would be a significant advancement in reliable and efficient modeling of physical phenomena in upper atmospheric flight. It could be used by both government and industry researchers to help design and analyze trans-atmosphericvehicles, new micro-propulsion systems, plumes, etc. Besides aerospace applications, the software will find numerous applications for several