Analysis of Active Flow Control Concepts Using the 3D LES VorCat Software

The goal of this project is to produce a revolutionary computational methodology that is fast, reliable and accurate for predicting complex high Reynolds number, turbulent flows associated with efficient aerodynamic designs. The proposed work will focus on low-speed canonical flows that introduce challenging physics, e.g., separation, transition and turbulence onset/progression, vortex/viscous interactions, merging shear layers with strong curvature, juncture flows, etc.. The extension of our proposed methodology to compressible flows has already begun and will be pursued in Phase II and beyond. The VorCat implementation of the gridfree vortex method is particularly attractive in this case since it efficiently represents near-wall vorticity producing motions while at the same time capturing the dynamics of the shed vorticity without numerical diffusion. An accurate and well resolved accounting of the boundary flow is crucial for controlling separation and other complex phenomena while unsteady free vortices are responsible for producing sound, downstream wing/vortex interactions and a range of other important phenomena. A number of previous published studies have established the unique benefits and accuracy of the VorCat vortex filament method. These include computations of ground vehicle flows, isotropic turbulence, shear layers, coflowing round jets, and boundary layers. Additional validation studies have been conducted in such applied settings as wind turbines, rotorcraft and particulate flows. Collectively, these results establish the effectiveness of the vortex filament scheme in capturing the flow structure and statistics for complex flow fields in a way that has not been duplicated by alternative grid-based methodologies. In the realm of vortex structure the VorCat approach has opened up a window into the dynamics of flow organization that is forcing a reassessment of some of the principal ideas concerning the physics of turbulent flow (J. Phys., 2011).