Dynamic subgrid-scale modeling for finite element based simulation of complex turbulent flows

Tran, Steven
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Sahni, Onkar
Oberai, Assad
Shephard, M. S. (Mark S.)
Tejada-Martínez, Andrés E.
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Aeronautical engineering
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The focus of this thesis is the formulation and development of a turbulence-resolving simulation tool based on finite elements. There are many challenges to the development of a reliable numerical approach for predicting the behavior of complex turbulent flows. In such flows, the difficulties emanate from two aspects: (i) complicated geometry and solution features and (ii) a balance between the computational cost and the amount of resolution and modeling that is required to perform accurate predictions. The finite element (FE) method has proven to be a valuable numerical tool to handle complicated features. Specifically, the ease with which the FE method can be applied on unstructured meshes makes it a powerful option for investigating many complex problems of interest. Furthermore, the adaptive meshing, high-order, and parallelization capabilities of the FE method can significantly increase the computational efficiency. In terms of turbulence resolution, direct numerical simulation (DNS) is the most reliable option but it requires a proper resolution of all the relevant turbulent scales (with no modeling). This makes DNS prohibitively expensive from a computational viewpoint for many problems of interest. An attractive alternative is large eddy simulation (LES) which resolves the flow structures on the order of the grid size and models the effects of the scales that are too small to be resolved by the grid (i.e., subgrid scales). %Therefore, LES involves subgrid-scale (SGS) modeling.
December 2016
School of Engineering
Dept. of Mechanical, Aerospace, and Nuclear Engineering
Rensselaer Polytechnic Institute, Troy, NY
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