Numerical simulation of late wakes in stratified and sheared flows

We employ high-resolution DNS methods to examine the dynamics, energetics, and structure of submarine wakes evolving to late times. Because of the computational focus of the project, our efforts are twofold: both computational efficiency and numerical accuracy. Thus our codes are highly optimized on the DoD computational platforms, scale linearly with increasing CPUs, and employ methods to achieve high computational efficiency. Emphasis in the wake simulations is placed on quantifying the differences between wakes of towed and self-propelled bodies and the influences of environmental shear and stratification. Results indicate that both source and environmental conditions can profoundly impact wake structure and evolution. Wakes of towed bodies lead to larger-scale coherent structures at late times, stratification confines wakes vertically and enables internal wave radiation, and shear organizes wake vorticity and interrupts the upscale cascade occurring in its absence.