The Bhatnagar–Gross–Krook operator (abbreviated BGK operator) term refers to a collision operator used in the Boltzmann equation and in the lattice Boltzmann method, a computational fluid dynamics technique.
In the context of fluid dynamics, the Bhatnagar–Gross–Krook (BGK) term denotes a collision operator utilized in both the Boltzmann equation and the lattice Boltzmann method.