Evaluation of the external force term in the discrete Boltzmann equation

A representation of the forcing term in the Boltzmann equation based on a Hermite expansion of the Boltzmann distribution function in velocity phase space is derived. Based on this description of the forcing term, a systematic comparison of previous lattice Boltzmann models describing a nonideal gas behavior is given. {copyright} {ital 1998} {ital The American Physical Society}