Case Study: A New Mesh Adaptation Procedure That Really Works

Pointwise and ISimQ developed an efficient adaptation procedure for effective control of discretization error on real-world cases that adapts to underlying geometry while still efficiently resolving the mesh with high aspect ratios in boundary layers. Shown here are results computed using ANSYS CFX on an adapted Pointwise mesh showing shear stress on the hub.

The adaptation procedure separates the meshing and solving steps in a coordinated and automated way managed by an overall adaptation program. It accomplishes several benefits. In the first step, the analyst creates an initial mesh to start the adaptation procedure. This initial mesh should resolve the near-wall boundary layer regions adequately. For example, Pointwise’s T-Rex (anisotropic tetrahedral extrusion) approach automatically creates regions of hexahedral mesh layers with high aspect ratio for computational efficiency, accuracy and robustness reasons in this area. The initial mesh generation step controls the target near-wall distance, 𝑦+, thereby removing this task from the mesh adaptation procedure.

Adapted mesh on the hub surface of the Aachen Turbine.

The adaptation software calculates and forwards a point cloud of target edge lengths to the Pointwise meshing software, augmenting the user-defined initial mesh generation state. The meshing software then generates an improved mesh to achieve the desired distribution of local target edge length. The adapted mesh preserves the initial user-defined mesh settings, and most importantly, the boundary layer meshing strategy. The adapted mesh inherently conforms to the underlying geometry known by the mesh generator. The mesh quality consistently improves with each mesh adaptation cycle, as the point cloud data consistently refine the mesh and no a priori choice of a “local subdivision” is necessary. As a bonus, the adaptation process naturally identifies and corrects areas of large mesh expansion ratio.

Read the full case study on the Pointwise website (no registration required).

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