SMS:Triangular Patch

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File:Triangular patch.gif

Elements can be made to fill a triangular area by choosing the Triangular Patch option from the Elements Menu. To define a triangular patch, three nodestrings must be selected. The nodestrings must connect at the ends.

The coordinates of the new nodes on the interior of the patch are computed by constructing a partial bicubic Coons patch using the nodestrings as patch edges. This ensures that interior nodes are smoothly interpolated from the nodes making up the perimeter of the patch. The following options are available for each edge of the triangular patch:

  • Use original nodes. This option causes the original nodes from the nodestring to be used as corner nodes of elements along the boundary.
  • Distribute nodes. This option distributes the specified number of nodes as corner nodes of elements along the boundary. If elements already exist on the boundary, then this option is unavailable.
  • Bias. This is used with the Distribute nodes option. It causes the spacing of nodes along the nodestring to be weighted more to one of the corners.

All three sides of a triangular patch must have the same number of nodes. After the spacing on each side is defined, click the Preview button to see how the patch will look. If changes are desired, they can be made. When the patch looks good, click the OK button to accept it. The patch can be canceled by clicking the CANCEL button. Be careful to use the preview button because THERE IS NO UNDO FOR THIS OPERATION.

The elements in a new patch are checked to make sure they do not overlap each other. If any problems are detected, an error message is given and the patch is not created. Errors may occur especially when the region is highly irregular in shape. In such cases, the region can either be divided into smaller patches, or it can be filled using a different mesh generation technique.

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