Simulation of the Enskog equation à la Bird

We present a modification of a recently proposed Monte Carlo simulation method [J. M. Montanero and A. Santos, Phys. Rev. E 54, 438 (1996)] to numerically solve the Enskog equation for a dense hard-sphere fluid. While in the original method momentum and energy are conserved by collisions only on average [as happens with Nanbu’s scheme of the direct simulation Monte Carlo (DSMC) method for solving the Boltzmann equation], the modified algorithm (that extends Bird’s null-time-counter version of the DSMC method) preserves exactly the conservation laws. Both methods are applied to fluids under shear for a wide range of densities. The agreement with the theoretical predictions for the shear viscosity and the viscometric coefficients is found to be excellent.