A New Approach to Anisotropy in Wall-turbulent Shear Flow, and with Application to Organised Disturbances, When these are Present

This paper takes a re-look at anisotropy in wall-turbulent shear flow, from the viewpoint of the primitive equations for turbulence, i.e. without considering averages. The paper attempts to develop some simple rules for the anisotropic part, and arrives at a logical definition of eddy viscosity and the turbulent shear stress tensor. The results are extended to the constitutive equation for organised disturbances in turbulent shear flows, when such disturbances are present. The model of Sen and Veeravalli (Sadhana,1998, 2000, 2007), for organised disturbances, seems to be vindicated.