Specifying Initial Mesh Settings

You can specify the initial mesh settings, including the surface approximation and the meshing approach for both Maxwell 3D and Maxwell 2D designs. Initial Mesh Settings 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.

For most Maxwell 3D designs, you can let the solver automatically choose which of two meshing approaches to take. Each solver predicts which one gives the best results, balancing mesh reliability, speed, quality, size and design characteristics.

In most cases, Maxwell uses TAU mesh, rather than the classic mesh. In general, it looks for specific features (for example, stacks of large planar parallel facets with small gaps) and situations where the initial Tau mesh is 4 times larger than the Classic. For Maxwell 2D designs, the TAU mesh is used.

In a few cases, you may decide to override the automatic choice and designate the mesher to use. To do so:

1. Access the Initial Mesh Settings one of two ways:
• Select Maxwell > Mesh > Initial Mesh Settings...
• In the Project Manager, right-click Mesh, and select Initial Mesh Settings from the shortcut menu.
• On the Simulation tab of the ribbon, select Mesh Settings.



The Initial Mesh Settings window appears, with the General tab selected.



2. For Maxwell 3D, the Mesh Method options you can select are:
• Auto – the solver automatically selects the mesher. This is the default setting. In most cases, this will be TAU.
• TAU – only specific curve faces will be remeshed (for example, equation-based axisymmetric faces). If a curve face connects to non-remeshed curve faces, the curve face will not be remeshed. If a curve face cannot be remeshed, faceting triangles will be used as the surface mesh. Mesh quality depends on how the faceting triangles are made. If the surface mesh is generated by TAU, it shows in the profile as Mesh TAU (Surface). If you check Use alternative mesh methods as fall back on the Advanced tab, this can fall back to Mesh TAU(Wrapper). This, in turn, can fall back to Mesh (stitch), which is classic.
• Classic – Classic mesh uses a Bowyer algorithm to create compact meshes for the model with very large length scales. It represents the model very accurately. Depending on the model, Classic mesh may converge using fewer resources whereas TAU or Phi Plus may converge faster. This setting must be used if you wish to use the Phi Mesher, for which you must also check Allow Phi for layered geometry (Classic only) on the Advanced tab.

For Maxwell 2D, the TAU mesher is used; there are no selection options.

3. For Maxwell models with curved surfaces, you can select or deselect Apply curvilinear meshing to all curved surfaces. This increases accuracy, but costs more memory.
4. Under Curved Surface Meshing, you can choose to Use dynamic surface resolution, select Use Slider or specify Manual Settings.

If you select Use dynamic surface resolution, the Manual Settings option is disabled.

The slider includes a visual representation of your choice, ranging from a Coarse Resolution (with a Small Mesh Count) through a nine position scale to a Fine Resolution (with a Large Mesh Count. Here, "Mesh Count" refers to the number of elements comprising the mesh.

Selecting Use dynamic surface resolution in the Curved Surface Meshing section specifies the best-practice mesh operations over the geometric models. This mesh operation will support 3D volume mesh and surface mesh in all products. The default mesh operations or user-defined mesh operations may or may not be replaced by the optimized mesh operations with model analysis. In general, large curve faces, curve faces with small gaps, or skewed cables get more smooth curvature representation while small curve faces, such as fillets, small curve objects, and so forth, get relatively coarse triangulations so that the overall mesh count will be reduced.

If you select dynamic surface resolution, you can optionally use the slider bar to adjust surface representation levels as: coarse (1-3), normal (4-6), and fine (7-9). You can also adjust the surface representation level for a specific group of faces by specifying slider bar, as described in Modifying Surface Approximation Settings.

5. If you choose Manual Settings, the window changes to show text fields. See: Modifying Surface Approximation Settings.



Use the check boxes to enable the fields and specify values:

• Surface Deviation – the distance between the true surfaces of the selected faces and the meshed faces.
• Normal Deviation – the angular distance between the normal of the true surface and the corresponding mesh surface. Maxwell 3D's default normal deviation setting for the selected faces is 15 degrees. Maxwell 2D's default normal deviation setting is 3 degrees.
• Aspect Ratio – determines the shape of the triangles. The higher the value, the thinner the triangles. Values close to 1 will result in well-formed, wide triangles. Maxwell’s default aspect ratio settings for the selected faces are 10 for curved surfaces and 200 for planar surfaces.
• Clicking Convert to Slider Value converts the manually entered values to an equivalent slider setting, and returns the panel to the slider view.
6. To make your choices the default, use the Save as default check box.
7. The Advanced tab lets you optionally specify a Set Length for Model Resolution. This is for experienced users who have a good understanding of how particular values will affect their models. In general, the Auto setting provides good results.



8. Use Flex meshing for TAU volume mesh enables a version of the TAU mesher that will rarely fail to generate a mesh (for Maxwell 3D models only). In most cases, the TAU Flex mesh is as accurate as traditional TAU or Classic meshes. However, for some complex models with bad translation or poorly defined surfaces that would fail to produce a strict mesh on all objects, relaxed tolerances will be applied. In these cases the user should review the mesh to evaluate whether it is acceptable for simulation. See TAU Flex meshing for more details.



Note:

TAU Flex meshing does not support RMxprt models.

9. Use legacy faceter for TAU volume mesh (for both Maxwell 2D and 3D models) – By default, TAU uses the latest faceter to generate geometric model for meshing. Occasionally, the mesher may fail, and TAU will automatically fall back to use the legacy faceter to make a second attempt. In such cases, directly using the legacy faceter can get the mesh in the first attempt so total meshing time will be saved. The legacy faceter is not actively maintained by Spatial and will be retired soon. This option should be used only as a last resort.
10. For Maxwell 3D models only, selecting Use alternative mesh methods as fall back enables the TAU and Classic mesh methods (chosen on the General tab) to fall back to alternative mesh methods if the solver fails to generate the initial mesh.

    You can also select Allow Phi for layered geometry (Classic only), which enables the Classic mesh method (chosen on the General tab) to use the Phi mesher for layered geometry.

    

    For example, the the sequence of mesher methods might go like this: When the mesh method is TAU: TAU(>Phi)>Classic. When mesh method is Classic: Classic(>Phi)>TAU. Note: the options do not affect the Auto mesh setups.

11. Click OK to apply your choices.

The settings will be applied to the initial mesh generated.