Several advanced production and measurement facilities comprise high vacuum systems as well as gas flows in nanochannels. The common challenge posed on simulation methods by such systems is to efficiently model the so called intermediate Knudsen number (Kn) regime. Here, the relevant scales approach the mean free path of particles and continuum assumptions become invalid.
We have developed a hybrid simulation model integrating a lattice Boltzmann method adapted for the intermediate Kn regime with a Monte Carlo (MC) algorithm. Therein the lattice Boltzmann method is utilised to simulate the fluid flow in complex geometries. The MC algorithm is used to model lower concentrations of contaminants in this background flow. This allows to take into account thermal effects, e.g. diffusivity.
In this contribution we present physics benchmarks validating the model as well as results of its application to contaminant transport in rarefied gas flows in complex geometries.