Large eddy interactions in curved wall boundary layers: Model and implications

An analytical framework, called the Large Eddy Interaction Model (LEIM), has been developed based on the identification of large eddies that undergo changes in a flow on account of interaction with the mean flow and the spectrum of eddies present in the turbulence. The mean flow may, in general, involve inhomogeneous shear, such as in a boundary layer flow. The eddy-eddy interactions give rise to transport process, which may be modelled on the basis of simple gradient diffusion or alternatively, the hypothesis of a velocity scale for the evolution of the turbulence field. The structure of a large eddy can then be utilized to determine various aspects of the structure of turbulence under given initial and boundary conditions. Curved wall boundary layers present an important case of complex turbulent flows. Considering four sets of experimental data available on variously curved wall flows, the applicability of LEIM has been tested. In each case the objective has been to obtain turbulent stress distributions, stress ratios and anisotropy as well aas the deformation of the eddy in terms of wave number and orientation.