BGK collision operator

Summary

The BGK collision operator is a simple model of the collision term of the Boltzmann equation. It replaces the quadratic collision integral by a relaxation of the distribution function towards the local Maxwell–Boltzmann distribution with the same density, velocity and temperature. It keeps the conservation of mass, momentum and energy and the H-theorem, but is much easier to analyse and to compute with. It was introduced by Bhatnagar, Gross and Krook in 1954 and underlies the lattice Boltzmann method. See the definition.