Simcenter STAR-CCM+ Example of anisotropic sizing for feature edges of surface meshes for rudders and wings

Summary

The present article provides an example of leveraging the new anisotropic sizing control (v16.06 upwards) for quad-surface meshes used to generate the polyhedral volume meshes for lifting surfaces like ship rudders or aircraft wings.

Details

Attachments:

anisoNNS_1@meshed.zip (594 MB)

The present article provides an example of leveraging the new anisotropic sizing control (v16.06 upwards) for quad-surface meshes used to generate polyhedral volume meshes of lifting surfaces like ship rudders or aircraft wings.
The feature allows for controlling grid spacing of the surface mesh in chordwise and spanwise direction separately, enabling a small grid spacing to resolve the curvature or edge of the lifting surface, and growing coarser along the edge and in chordwise direction.
Below is an example of a surface mesh with anisotropic sizing for submarine rudders for which feature edges were available along the chord, leading and trailing edge. It requires the surface mesh to be set to quad-dominant. The quad-dominant surface mesh of the rudder is shown in gold, the one for the submarine hull in green. A plane section cuts through the volume mesh and shows the positive effect the anisotropic sizing of the edge of the surface mesh has on the construction of prism layers in the volume mesh.

    
The controls in Simcenter STAR-CCM+ follow concepts in place for building prism layer meshes, where the size of a first layer is specified, and one can set a stretching factor and distance to grow the layers until the core mesh. The specifics of the controls are outlined below. Go to Parts > Operations > Automated Mesh > Custom Controls to reproduce below tree menu.

 
The feature is enabled by creating a new custom feature curve control and check the box under Controls > Anisotropic Sizing. Once enabled there are three controls driving the mesh creation. The first two are “Growth Ratio” and “Number of Constant Layers”, available from selecting the Anisotropic Sizing node. A child node emerges called “First Layer Thickness” which determines the distance from the feature edge to the opposing face of the first layer cell, equivalent to “Wall Thickness” for the prism layer mesher. The “Number of Constant Layers” can be used to extend this level of grid spacing to a user-defined number. The “Growth Ratio” will determine how fast grid spacing is growing from the last constant layer to the core mesh grid spacing.

 

It is recommended to deactivate Perform Curvature Refinement and Perform Proximity Refinement in the Surface Remesher settings. By disabling the curvature and proximity controls, the mesh is refined using only the anisotropic size control applied on the part curves, avoiding conflicts and undesired mesh outcomes.


Pre-Processing > Meshing > The Meshing Workflow > Anisotropic Sizing for Wings and Blades