Structural approach to the modeling of a turbulent mixing layer

This paper combines a structural approach by deriving a turbulent coherent structure-which we call an eigenlet-as an eigenfunction of the Navier-Stokes equations, with a new (curl-type) eddy viscosity model (which is more representative of intermediate scales than the classical Boussinesq eddy viscosity) to describe a fully developed turbulent mixing layer without using any empirical input. This result is achieved by invoking the self-consistency condition that the mean flow and the eigenlet have the same spread angle. Using self-similar variables and the modeled equations, we obtain the mean flow and the eigenlet. Several flow features, such as Reynolds stress, mixing layer spread and inclination angles, and the average structure passage frequency have been calculated; these results are in good agremeent with experimental data.