Direct simulation Monte Carlo

Direct simulation Monte Carlo (DSMC) method uses probabilistic (Monte Carlo) simulation to solve the Boltzmann equation for fluid flows.

The DSMC method was initially proposed as a method for predicting rarefied gas flows where the Navier-Stokes equations are inaccurate and it has now been extended to near continuum flows. The method models fluid flows using simulation molecules which represent a large number of real molecules in a probabilistic simulation to solve the Boltzmann equation. Molecules are moved through a simulation of physical space in a realistic manner that is directly coupled to physical time such that unsteady flow characteristics can be modelled. Intermolecular collisions and molecule-surface collisions are calculated using probabilistic, phenomenological models. The fundamental assumption of the DSMC method is that the molecular movement and collision phases can be decoupled over time periods that are smaller than the mean collision time.

Currently the DSMC method has been applied to the solution of flows ranging from estimation of the Space Shuttle re-entry aerodynamics, to the modelling micro-electro-mechanical systems (MEMS).