ON EXPLICIT ALGEBRAIC STRESS MODELS FOR COMPLEX TURBULENT FLOWS

Explicit algebraic stress models that are valid for three-dimensional turbulent flows in non-inertial frames are systematically derived from a hierarchy of second-order closure models. This represents a general ization of the model derived by Pope (1975) who based his analysis on the Launder, Reece & Rodi model restricted to two-dimensional turbulen t flows in an inertial frame. The relationship between the new models and traditional algebraic stress models - as well as anisotropic eddy viscosity models - is theoretically established. A need for regulariza tion is demonstrated in an effort to explain why traditional algebraic stress models have failed in complex flows. It is also shown that the se explicit algebraic stress models can shed new light on what second- order closure models predict for the equilibrium states of homogeneous turbulent flows and can serve as a useful alternative in practical co mputations.