Towards Automated Hybrid-prismatic Mesh Generation

Abstract

An open-source implementation of an efficient mesh generation procedure for hybrid prismatic-tetrahedral meshes intended for use in Reynolds-averaged Navier-Stokes solutions is presented. The method employed combines the established, and very fast, Delaunay-based tetrahedral mesh generator TetGen with a novel technique for the creation of a prismatic layer. Satisfactory mesh quality is demonstrated by comparing solutions obtained using the new meshes with reference data computed on advancing-front grids. Mesh generation time is shown to be substantially less than with some other methods. Overall, the presented implementation is deemed a valuable tool for cases where many meshes need to be generated for routine analyses and turnaround time is critical.

Grid Generation and Fluid-Solid Coupling Methods for the Investigation of Gas Turbine Rotor Blade Internal Cooling

“…The whole-layer-inflation approach can be more efficient than the previous approach since in this algorithm the viscous cells no longer need to be checked layer-by-layer and the generation process can be very fast [9]. However, as this algorithm tries to generate the same number of prismatic layers for the whole model, or at least for the same surface, it requires a set of additional operations to "fix" the invalid elements.…”

“…For instance, this algorithm is often associated with a shrinking procedure to retain the validity of viscous elements in the region where intersection with other elements of the front appear. This is accomplished by progressively reducing the total thickness of the layer [38,9]. This kind of thickness reduction usually leads to a steep transition between the prismatic and tetrahedral elements, and locally modifies the stretching ratio of all the layers in narrow or highly constrained regions.…”

“…The Outer Layer Boundary checking procedure is conducted in a similar way as as the inflated approach [57], but its purpose is to identify the cells which will not pose intersection problems rather than generating a proper valid mesh. Then, the checking process has only to be applied to those cells for which the OLB checking failes, drastically reducing the total number of checking and, therefore, the computational cost.…”

“…However, the meshing process for a complex 3D model with such a large mesh size is usually very timeconsuming. Even for experienced engineers, it may take days to weeks to create a mesh for a very complex internal cooling geometry [9,10]. When considering extra uncertainties coming from badly parametrised entities in practical applications, non watertight models, etc, a great waste of engineering hours and long meshing turn around time are frequent.…”

“…Once the viscous grid is generated, the last front of the viscous mesh is passed to the volumetric mesh generator to fill the rest domain with isotropic tetrahedral elements. This procedure is opposed to the practise of generating all layers at once, and then checking/fixing invalid elements at the end [32,9]. The layer-by-layer approach was found to be more robust since trying to generate all layers at the same time would encounter some difficulties because of complex geometries.…”