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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 – Method

By default, the application uses the Automatic Method control, which attempts to use sweeping for solid models and quadrilateral element generation for surface body models.

## Ansys Meshing – Fine Mesh

Available when Use Adaptive Sizing is set to Yes, the Resolution option controls the mesh distribution. The default setting is Program Controlled.

## Ansys Meshing – Mapped & Match Control

The Match Control matches the mesh on two or more faces or edges in a model. The Meshing application provides two types of match controls—cyclic and arbitrary.

## Ansys Meshing – Section Plane

Meshing is an integral part of the engineering simulation process where complex geometries are divided into simple elements that can be used as discrete local approximations of the larger domain. The mesh influences the accuracy, convergence and speed of the simulation.

## 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.

## 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.

If the Sphere of Influence is scoped to a body or vertex, the Sphere of Influence affects the entire body regardless of sizing options being used.

## Ansys Meshing – Sizing

For solid models, meshing technologies from ANSYS provide robust, well-shaped quadratic tetrahedral meshing on even the most complicated geometries.

## Ansys Meshing – Refinement Mesh

For solid models, meshing technologies from ANSYS provide robust, well-shaped quadratic tetrahedral meshing on even the most complicated geometries.

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