# Bhatnagar–Gross–Krook operator

(Redirected from Bhatnagar-Gross-Krook)
$\Omega_i=-\tau^{-1}(n_i-n_i^{EQ})$
where $n_i^{EQ}$ is a local equilibrium value for the population of particles in the direction of link $\mathbf{e}_i$ The term $\tau$ is a relaxation time, and related to the viscosity.