| Title: | A new two-scale model for large eddy simulation of wall-bounded flows |
| Author: | Gungor, Ayse Gul |
| Abstract: | A new hybrid approach to model high Reynolds number wall-bounded turbulent flows is developed based on coupling the two-level simulation (TLS) approach in the inner region with conventional large eddy simulation (LES) away from the wall. This new approach is significantly different from previous near-wall approaches for LES. In this hybrid TLS-LES approach, a very fine small-scale (SS) mesh is embedded inside the coarse LES mesh in the near-wall region. The SS equations capture fine-scale temporal and spatial variations in all three cartesian directions for all three velocity components near the wall. The TLS-LES equations are derived based on defining a new scale separation operator. The TLS-LES equations in the transition region are obtained by blending the TLS large-scale and LES equations. A new incompressible parallel flow solver is developed that accurately and reliably predicts turbulent flows using TLS-LES. The solver uses a primitive variable formulation based on an artificial compressibility approach and a dual time stepping method. The advective terms are discretized using fourth-order energy conservative finite differences. The SS equations are also integrated in parallel, which reduces the overall cost of the TLS-LES approach. The TLS-LES approach is validated and investigated for canonical channel flows, channel flow with adverse pressure gradient and asymmetric plane diffuser flow. The results suggest that the TLS-LES approach yields very reasonable predictions of most of the crucial flow features in spite of using relatively coarse grids. |
| Type: | Dissertation |
| URI: | http://hdl.handle.net/1853/29764 |
| Date: | 2009-05-14 |
| Publisher: | Georgia Institute of Technology |
| Subject: |
Turbulent flows
Large eddy simulations Two-scale model Wall-bounded flows Near-wall modeling Incompressible flows Eddies Navier-Stokes equations Fluid dynamics Computational fluid dynamics |
| Department: | Aerospace Engineering |
| Advisor: | Committee Chair: Menon, Suresh; Committee Member: Ruffin, Stephen; Committee Member: Sankar, Lakshmi; Committee Member: Stoesser, Thorsten; Committee Member: Yeung, Pui-Kuen |
| Degree: | Ph.D. |
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