A Core Spreading Vortex Method Suitable for Long Time Simulations of 2D Flows over a Body of Arbitrary Shape
Date Issued
2011
Date
2011
Author(s)
Huang, Chien-Jung
Abstract
In this thesis, a core-spreading vortex method suitable for a long-time simulation of 2D flows over an arbitrary body is successfully developed. In this vortex method, we employ the splitting and merging skills to control the convection error, an imposition of a vortex sheet on the body to enforce the no-slip boundary condition, the fast vortex method to speed up the computation, and finally the boundary element method to provide the geometry flexibility. This thesis particularly aims at improving the long-time accuracy of the vortex method. Firstly, for the over-weak blobs generated due to blob splitting, we remove them and distribute their strength to nearby non-over-weak blobs through a near-to-far algorithm using the merging grids. Secondly, we determine the appropriate approximation solution and optimized discretization of the vortex sheet diffusion. Thirdly, for treatment of the near-wall blobs, we redefine the near-wall region, which enables the simulation of flows over bodies of arbitrary shape. Finally, an outflow boundary condition is designed and imposed to control the total blob number. The flow induced by the impulsively started airfoil, circular, and elliptic cylinders are simulated and the accuracy and efficiency of the proposed vortex method are confirmed by the agreement between the present simulation results and those in the literatures.
Subjects
Core-spreading vortex method
Arbitrary shape
Outflow boundary condition
Boundary element method
Type
thesis
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