This thesis presents a two- and three-dimensional unstructured viscous grid generation technique. The methodology is based on the Advancing-Front Method for the generation of 'Euler' tetrahedral grids and the Advancing- Layers Method for producing highly stretched tetrahedral grids suitable for viscous flow calculations.
Advancing-Layers Method relies on a totally unstructured grid generation strategy benefiting from a high degree of flexibility required for generating grids around complex geometries. A simple iteration scheme has been used to resolve the crucial problem of computing surface vectors in 3D. A straightforward front-detecting procedure based on the 'spring' analogy is also used to eliminate the need for an expensive face-cross check algorithm for generation of viscous grids, resulting in an increased efficiency as compared with the conventional Advancing-Front Method.
In the present study, every step of grid generation technique for simple geometries is presented to demonstrate the capability of the method. Viscous grids of Douglas 3-element airfoil and Oneram6 wing are generated and the flows are computed for validations. The results show good agreements with experimental data with reasonable number of grid points. This method is robust, efficient, and automatic, capable of constructing highly stretched viscous tetrahedral grids.