Activating Trimmed Cell Mesh Support for Adaptive Mesh Model

If you generate the mesh using the Trimmed Cell Mesher, the Adaptive Mesh solver can recognize trimmed cell refinement levels (octant depths) and honor them during refinement. This recognition helps to improve the quality of cell sub-division and child cell quality. The procedure is called Trimmed Cell Mesh Support.

However, the Trimmed Cell Mesher and AMR are not fully compatible. Before running the Adaptive Mesh model for a trimmed cell mesh, you are advised to check the unrefinable cells in your solution domain. Most unrefinable cells are the ones with different octant depths, but sharing a common face. To avoid them, you are advised to generate cells with possibly same size around curved objects.

In case of large number of unrefinable cells in critical areas, where refinement is expected, turn off the Trimmed Cell Mesh Support so that a classic mid-point subdivision is applied to all the cells in the solution domain.

To activate the Trimmed Cell Mesh Support:
  1. For meshes generated by the Trimmed Cell Mesher, select the Models > Adaptive Mesh node and set the Initial Mesh to Trimmed (HEX).
  2. For unknown mesh sources, set Initial Mesh to Auto Detect.
    Auto Detect checks whether the mesh is compatible with Trimmed Cell Mesh Support. If it is, Trimmed Cell Mesh Support is activated. If it is not compatible, the Adaptive Mesh solver treats all the cells with refinement level 0, just like the option General. See Initial Mesh Properties.
To identify unrefinable cells, populate the Adaptive Mesh field functions:
  1. Right-click the Solvers > Adaptive Mesh node and select Evaluate Refinement Status.
  2. To mark the unrefinable cells in the trimmed mesh due to inconsistencies with neighboring cells, you create a threshold part with the value 4.0 using the field function Adaption Refinement Status.
    1. Right-click the Derived Parts node and select New Parts > Threshold
    2. In the pop-up Create Threshold dialog, set the properties as follows:
      Property Value
      Scalar Adaption Refinement Status
      Extraction Mode All Between
      Scalar Range [4.0,4.0]
    3. To visualize the unrefinable cells, create a scalar scene to display the [threshold] with the scalar function Adaption Refinement Status.
    An example result is shown below:


Usually, a small number of unrefinable cells does not cause significant loss of accuracy in the solution—these cells can not be refined by AMR model. But they are not disabled in the solution domain. If the number of unrefinable cells appear in critical areas, you are advised to switch off the Trimmed Cell Mesh Support:
  1. Select the Models > Adaptive Mesh node and set the Initial Mesh to General.
NoteTo avoid a significant number of unrefinable cells, you are advised to always reset the mesh when you clear adaption before reactivating Trimmed Cell Mesh Support.