HFSS15: Modifying Surface Approximation Settings

HFSS applies surface approximation settings for selected objects when it generates the initial mesh. If you modify HFSS’s default settings after the initial mesh has been generated, they will not affect the mesh for that design variation. Surface approximation makes sense for curved surfaces, for which the mesh will not exactly reproduce the surface shape. It also can be used to restrict the aspect ratio of triangles on planar surfaces.

1. Select the faces for which you want to modify the surface approximation settings.

Alternatively, select an object if you want to modify the surface approximation settings of every face on the object.

2. Click HFSS>Mesh Operations>Assign>Surface Approximation.

The Surface Approximation dialog box appears with the Surface Approximation tab select..

3. Type a name for the group of settings in the Name text box or accept the default name.

4. Under Maximum Surface Deviation, do one of the following:

• Select Ignore if you do not want to use surface deviation settings for the selected faces.

• Select Set maximum surface deviation (length), and then type the distance between the true surfaces of the selected faces and the meshed faces in the text box.

5. Under Maximum Surface Normal Deviation, do one of the following:

• Select Use defaults if you want to use HFSS’s default normal deviation setting for the selected faces, which is 22.5 degrees.

• Select Set maximum normal deviation (angle), and then type the angular distance between the normal of the true surface and the corresponding mesh surface in the text box.

6. Under Maximum Aspect Ratio, do one of the following:

• Select Use defaults if you want to use HFSS’s default aspect ratio settings for the selected faces, which are 10 for curved surfaces and 200 for planar surfaces. A ratio of 200 corresponds roughly to a triangle with an interior angle of one half degree.

• Select Set aspect ratio, and then type a value in the text box. This value determines the shape of the triangles. The higher the value, the thinner the triangles. Values close to 1 will result in equilateral triangles.

7. Select the Surface Representation Priority for Tau Mesh:

In most cases, meshing is done by Tau Mesh. (See Initial Mesh Settings.) You can set the surface representation as normal or high.

• Normal - use for normal situations for the Tau Mesh, allowing loose tolerances.

• High - Use only on critical surfaces. (For example, a very small port in a large model.) The choice of "High" can help to mesh some difficult or small surfaces, but it can also be very expensive and can cause the mesher to fail.

8. Click OK.

The settings will be applied to the initial mesh generated on the selected surface. The group of settings is listed in the project tree under Mesh Operations.

You can also specify Initial Mesh Settings to apply to all objects; however, if you apply separate surface approximation mesh operations to specific objects, the object settings take precedence over the general setting.