Molecular dynamics simulation of piston-driven shock wave in hard sphere gas

Molecular dynamics simulation is used to study the piston-driven shock wave at Mach numbers 1.5, 3, and 10, A shock tube, whose shape is a circular cy linder, is filled with hard sphere molecules having a Maxwellian thermal ve locity distribution and zero mean velocity. The piston moves, and a shock w ave is generated. The work is intended as an important test case of the app lication of molecular dynamics in fluid mechanical problems in a manner tha t avoids imposing statistical boundary conditions. Therefore, all collision s are treated as elastic, including those between the molecules and the com putational boundaries, so that the shock development is entirely causal. Th e propagation and structure of the shock is examined in detail, and the wav e speed; profiles of density, velocity, and temperature; and shock thicknes s are determined. The results are compared with published results of other methods, especially the direct simulation Monte Carlo (DSMC) method. Proper ty profiles are similar to those generated by DSMC. Shock thicknesses are s maller than DSMC results but larger than those of the other methods.