Use of the Monte Carlo method to calculate the flow of a highly rarefied gas in systems with arbitrary wall configuration

A method is described for modeling collisions of gas molecules with the walls of a system whose geometry is given numerically in the computer memory from a graphical representation of the walls (for example, from their working drawings). When changing from the calculation of one system to another only the information on the wall changes; the computational program remains the same. The method is applicable to problems of rarefied gasdynamics which are solvable by the Monte Carlo method; in the following it is used to calculate the conductance of elements of high vacuum lines and the compression ratio created by molecular vacuum pumps, and also to calculate the forces acting on a body which rotates in a cavity filled with a highly rarefied gas.In conclusion the authors wish to thank Yu. I. Neimark for formulating the problem and discussions of the results obtained.