Modeling Thermally Driven Flow Problems with a Grid-Free Vortex Filament Scheme: Part I

Report No. ARL-TR-8296
Authors: Pat Collins; Peter Bernard; Ben MacCall
Date/Pages: February 2018; 56 pages
Abstract: Grid-free representation of turbulent flow via vortex filaments offers a means for large eddy simulations that faithfully and efficiently account for the essential physics of vortex stretching and organized vortical structures without the debilitating effects of numerical diffusion and eddy viscosity modeling. Backscatter is accommodated and the vortices that form remain sharp as they convect and distort in the flow field. In this project a second-generation implementation of the vortex filament scheme has been developed that offers a major acceleration in speed, parallel efficiency through an efficient distribution of vortices across processors, and a new, fast multipole method based in part on the open-source EXAFMM. Moreover, provision has been made to include grid-free energy particles and thus a capability of capturing 2-way coupling between momentum and energy via barotropic vorticity generation associated with thermal gradients. The validation studies have focused on natural convection following a release of energy into a stagnant field and show that this new method is capable of capturing the correct physics of 3-D natural convection problems.
Distribution: Approved for public release
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Last Update / Reviewed: February 1, 2018