A new procedure for the simulation of unsteady turbulent flows using Galerkin finite element and adaptive grids is presented. The adaptive grids are generated during the simulation using a new mesh generation technique. This technique is fast, produces a quad-dominant mesh while preserving the quality of the elements without the need to move any grid points. The new points are nested to the old mesh to avoid hanging nodes. Interpolation operators are used to map the different variables from one grid to the next one. Refinement zones are defined using the gradient of the vorticity from the previous time step.
A Galerkin finite element method is implemented to simulate unsteady incompressible turbulent flows using the primary variables with mixed elements for the velocity components and the pressure. The resulting linearized system is solved using Krylov subspace iterative methods and multigrid. The least-squares commutator is implemented as a preconditioner of the indefinite linear system. The Wilcox k-ω turbulence model is implemented and the solver is coupled with the adaptive grid generator in order to produce a new solution resolved grid for every time step.
Several application examples are provided to show the strength of this new approach. These applications includes unsteady laminar and turbulent flows over various two-dimensional objects such as cylinders, a NACA0012 airfoil and a multi-element airfoil.
|Advisor:||Davis, Roger L.|
|School:||University of California, Davis|
|School Location:||United States -- California|
|Source:||DAI-B 69/11, Dissertation Abstracts International|
|Subjects:||Aerospace engineering, Ocean engineering|
|Keywords:||Adaptive grids, Incompressible flows, Turbulent flows|
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