A STUDY OF FAVRE AVERAGING IN TURBULENT FLOWS WITH CHEMICAL-REACTION

This article presents an investigation of the Favre averaging method for turbulent flows with chemical reaction. A set of data from direct numerical simulations of a chemically reacting turbulent mixing layer is employed. Favre-averaged quantities are compared directly with their corresponding Reynolds-averaged values. The gradient transport assumptions in the k - epsilon-model in Favre-averaged form are also tested. Finally the transport equations for the Reynolds stress and the scalar flux of the chemical product are studied term by term. Some Favre-averaged quantities such as approximately u, approximately c, and approximately k are very similar numerically to their Reynolds-averaged values. Other Favre-averaged quantities, however, like approximately epsilon and rho-BAR approximately u approximately upsilon, are significantly different from their Reynolds-averaged values. The gradient transport models generally work rather well when the mixing layer is in a naturally developing turbulent state, although some important weaknesses are noted. Some significant effects of pressure on the Reynolds stress rho-BAR approximately u" upsilon" and scalar flux rho-BAR approximately upsilon" c" are exhibited.