ON THE EXISTENCE OF A GENERALIZED LANGEVIN MODEL REPRESENTATION FOR 2ND-MOMENT CLOSURES

The Generalized Langevin model representations of two second-moment cl osure models for the rapid pressure-strain term, proposed by Fu and La under and by Jones and Musonge, are obtained. This representation make s it possible to use these models in PDF calculations of turbulent flo ws. The implications of three realizability constraints for the relati onship between Langevin models and these second-moment closures are di scussed. A Generalized Langevin model representation exists only if th e rapid pressure-strain model satisfies realizability at the 2D turbul ence limit. (C) 1996 American Institute of Physics.