Direct Simulation Monte Carlo for Rayleigh Flow

by Cosmin Safta, Department of Mechanical and Aerospace Engineering.

The computational domain is a box with Lx=Ly=2 and Lz=12.5 (the length unit correspond to the initial mean free path of 62.6nm). The gas (Argon) is initially at rest (T=273K, p=0.9atm), and at t=0 the wall (z=0) is impulsively starting to move in positive x-direction with the velocity u=167m/s. This simulation consists of 60,000 particles, each particle corresponding to 5 molecules in the physical space. A number of 1,000 realizations are performed, each with 125 time steps (about 1ns).

First movie shows the time evolution of the average Vx velocity profile. Second movie shows the evolution of the particle positions for one realization. Particles are colored corresponding to the average velocity in x-direction (Vx).

References:

• F.J. Alexander and A.L. Garcia. The Direct Simulation Monte Carlo Method. Computers in Physics, 11(6):588-593, 1997.

• Course notes (Spring 2000):

Movies in Windows Media Player format:

Average Velocity in X-Direction

Particles

Movies in Quicktime format:

Average Velocity in X-Direction

Particles