EFFICIENT SIMULATION OF AIRCRAFT EXHAUST PLUME FLOWS USING A MULTI- ELEMENT UNSTRUCTURED METHODOLOGY*

An efficient methodology for simulating aircraft exhaust plume flows using a multi-element unstructured grid strategy is presented. It is well understood that tetbased methods require prismatic layers to analyze wall boundary layers. This paper demonstrates that such tetbased methods are unsuitable for analyzing jets and free shear layers due to resolution requirements in the thin mixing layers. Simulations are described that illustrate the very large grid sizes required using traditional tetrahedral/prism unstructured grids for this class of problems. The multi-element approach described utilizes an optimal combination of tetrahedral, prism, pyramid, and hexahedral elements, providing an efficient unstructured grid approach to complex propulsive flowfields. Simulations are presented that show the versatility and efficiency of this method as applied to this class of problems. Earlier work has addressed the inclusion of advanced turbulent models and generalized thermochemistry into this multi-element framework.