Geometry Discretization
Description
This functionality holds geometry discretization values for all CAD bodies. It consists of Global and Local options.
Global
Resolution in X, Y and Z provides discretizing values in X, Y and Z directions. Minimum distance between keyplanes is used to remove the hard keyplanes within the specified distance. These values are saved with the active Electronics Thermal solution.
The user can define hard coordinate values (hard keyplanes) for an exact representation of important bodies (i.e., PCB traces, board thickness).
The user can confirm that the level of discretization is satisfactory by specifying the discretization deviation threshold (volume percentage) in Solution Parameters | Advanced Options. The CAD bodies with volumetric deviation greater than the specified threshold are identified and added to a separate body group. Discretization failed CAD bodies are added to a separate body group. All these body groups contain only the bodies identified in the last discretization.
By enabling the “Write vias as links” toggle in Solution Parameters | Advanced Options, we can skip the vias bodies from discretization irrespective of the local refinements or key planes defined to them. The toggle is disabled by default.
If an environmental variable "SIMLAB_RETAIN_GD" is set to TRUE
- The “Create discretized geometry” toggle is available in the "Geometry
Discretization" dialog as shown below
- If the “Create discretized geometry” toggle is ON, based on specified resolutions,
all CAD bodies in the active Electronics Thermal solution are discretized and a
geometry grid is created. Geometry Grid (also known as keyplane mesh) represents the
coarsest possible mesh of the CAD bodies and all elements are bricks with
equal/unequal size and edges are parallel to the global XYZ. By default, the mesh
lines (element edges) are hidden in discretized geometry and it can be enabled using
"CTRL+E" or "Render mode | Edge Display | Element Edge".
- When an active Electronics Thermal solution exists and it has empty mesh bodies, the geometry grid is automatically added to it. If the Solution already contains the discretized geometry in its mesh bodies, the message will be posted and based on the request, either existing discretized geometry will be retained or the newly discretized geometry will be automatically replaced in the solution mesh bodies and the transfer of all loads and boundary conditions is not supported for CAD based approach.
- For "Thermal and Flow", "Thermal and Frozen Flow" simulations, the “Display discretized air region” option will be shown in the “Geometry Discretization” dialog, it is used to display the created air body and it gets assigned with default fluid material in "Solution Parameters | Advanced Options".
- The material assigned to the CAD body is automatically transferred to its corresponding geometry grid body.
Local
Local option is used to specify resolution in X, Y and Z for the selected bodies.
Based on the specified name, this option is created as mesh control in the mesh control browser as shown below.
On discretization, bodies assigned with local option will be discretized based on their specified resolution and rest of the bodies will be discretized based on global resolution values. In the following image, highlighted body is assigned with 0.25mm of local resolution in X, Y, Z and rest of the bodies are discretized with global resolution of 1mm in X, Y and Z.
Hard Key Planes
Hard key plane must be defined prior to Geometry Discretization. It is created using Mesh | Controls | Mesh Planes
Hard key planes are used to capture the planar geometry better by means of creating hard planes on planar faces aligned parallel with any one of the global axis.
After selecting surfaces individually or collectively, hard key planes are created using Create option in Key Planes dialog and the Delete option is used to delete the selected key planes
Hard keyplane definition should be used sparingly as it can drastically increase the model size.