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Ansys Meshing – Mesh Types (Hexa, Prism, Polyhedral)

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Source: Ansys

When geometries are complex or the range of length scales of the flow is large, a triangular/tetrahedral mesh can be created with far fewer cells than the equivalent mesh consisting of quadrilateral/hexahedral elements. This is because a triangular/tetrahedral mesh allows clustering of cells in selected regions of the flow domain. Structured quadrilateral/hexahedral meshes will generally force cells to be placed in regions where they are not needed. Unstructured quadrilateral/hexahedral meshes offer many of the advantages of triangular/tetrahedral meshes for moderately-complex geometries.

A characteristic of quadrilateral/hexahedral elements that might make them more economical in some situations is that they permit a much larger aspect ratio than triangular/tetrahedral cells. A large aspect ratio in a triangular/tetrahedral cell will invariably affect the skewness of the cell, which is undesirable as it may impede accuracy and convergence. Therefore, if you have a relatively simple geometry in which the flow conforms well to the shape of the geometry, such as a long thin duct, use a mesh of high-aspect-ratio quadrilateral/hexahedral cells. The mesh is likely to have far fewer cells than if you use triangular/tetrahedral cells.

Converting the entire domain of your (tetrahedral) mesh to a polyhedral mesh will result in a lower cell count than your original mesh. Although the result is a coarser mesh, convergence will generally be faster, possibly saving you some computational expense.

In summary, the following practices are generally recommended:

• For simple geometries, use quadrilateral/hexahedral meshes.
• For moderately complex geometries, use unstructured quadrilateral/hexahedral meshes.
• For relatively complex geometries, use triangular/tetrahedral meshes with prism layers.
• For extremely complex geometries, use pure triangular/tetrahedral meshes.

In this tutorial we show the results of a heat transfer simulation using different types of meshes (Tetrahedral mesh vs Hex/Prism vs Polyhedral mesh). You will notice the differences between the number of elements and the results and the computational time.

## Ansys Meshing – Body of Influence

The Body of Influence option is available in the Type field if you selected a body and Use Adaptive Sizing is set to No. Using this option, you can set one body as a source of another body

## Ansys Meshing – Sphere of Influence

The Sphere of Influence option is available in the Type field after you select an entity such as a body, face, edge, or vertex.

## Ansys Meshing – Mesh Copy Control

The Mesh Copy control enables you copy mesh from one body to another. This option can be used to reduce the mesh setup time for repetitive bodies/parts. Association to CAD is maintained after performing mesh copy.

Mesh controls are scoped only to the source anchor body. When the mesh is generated, the source anchor body is meshed and the mesh is then copied to targets.

## Ansys Meshing – Pinch

The Pinch feature lets you remove small features (such as short edges and narrow regions) at the mesh level in order to generate better quality elements around those features.

## Ansys Meshing – Hexahedral Mesh (Pipe)

The MultiZone mesh method provides automatic decomposition of geometry into mapped (structured/sweepable) regions and free (unstructured) regions.

## Ansys Meshing – Element Order (Linear & Quadratic)

The global Element Order option allows you to control whether meshes are to be created with midside nodes (quadratic elements) or without midside nodes (linear elements).

## Ansys Meshing – CutCell

The CutCell meshing process involves the following approach:
Objects, material points (optional), and size functions are defined.
The initial size of the Cartesian grid is computed based on the minimum and maximum size set for the size functions.

## Ansys Meshing – Parallel Meshing

You can control three mechanisms in ANSYS Workbench that operate in a parallelized manner:
Remote Solve Manager Design Point updates. Refer to RSM Configuration.

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