Remeshing a Deformed Mesh

When the mesh deformation has become so large that the quality of the mesh is too bad, generate a new mesh for the deformed configuration and then continue the solution process. To do so, follow these steps:

1	Add a stop condition.

2	View the deformed mesh.

3	Copy the solution.

4	Create a Deformed Configuration ().

5	Remesh the deformed configuration.

6	Continue solving with the new mesh.

To make the Deformed Configuration mesh represent the deformed geometry, use a Moving Mesh (ALE) interface to model the mesh deformation or, for structural mechanics models, use the option in the study to include geometric nonlinearity (requires the Structural Mechanics Module, MEMS Module, or Acoustics Module). Also, some of the physics interfaces in the Corrosion Module and Electrodeposition Module include a deformed geometry.

• Deformed Configuration • Solution (data set)

The following sections contain details about these steps and additional information.

Adding a Stop Condition

Add a stop condition in the solver to make it stop when the mesh quality becomes too bad. If the Time-Dependent Solver is used, do this by right-clicking, for example, Study 1>Solver Configurations>Solution 1> Time Dependent Solver 1 and selecting Stop Condition () from the context menu. If the parametric stationary solver is used, right-click, for example, Stationary Solver 1>Parametric 1 under Solution 1 and select Stop Condition () from the context menu. In the table under Stop Expressions, enter a Boolean expression (to stop when the expression is true) or an expression that makes the solver stop when the expression becomes negative. For example, enter comp1.ale.I1isoMax>4 to stop before the maximum element distortion exceeds 4. Notice that you must add the component where the Moving Mesh (ale) interface is defined, in this case comp1 for Component 1, to access the variable from the Study branch (see Variable Naming Convention and Namespace).

The following predefined variables are useful for defining a stop condition and for monitoring the mesh deformation: the maximum element distortion, ale.I1isoMax; the minimum relative element volume, ale.relVolMin; and the minimum mesh quality, ale.minqual. See Predefined Variables below.

In time-dependent simulations, you can use automatic remeshing instead of the stop condition. The software then creates new meshes when the mesh quality drops below the specified level. To do so, click the Step 1: Time Dependent node () and then select the Automatic remeshing check box in the Settings window’s Study Extensions section. To use the same condition as for the stop condition above, select Distortion under Condition type, enter comp1.ale.I1isoMax in the Distortion expression field, and enter 4 in the Stop when distortion exceeds field in the Settings window for the Automatic Remeshing () node (under the Time-Dependent Solver node in the solver sequence).

Viewing the Deformed Mesh

Use a Mesh plot in a 2D or 3D plot group to visualize the deformed mesh. The Mesh plot shows the element shapes, sizes, and quality corresponding to the frame selected in the underlying data set. See Mesh (Plot) for details.

Copying the Solution

To keep the first solution, right-click Study 1>Solver Configurations>Solution 1 and select Solution>Copy (). The copied solution appears as a new solution; Copy 2, for example.

Creating a Deformed Configuration

Create a deformed configuration by right-clicking, for example, Results>Data Sets>Solution 2 and selecting Remesh Deformed Configuration (). The deformed configuration appears as a new Deformed Configuration node () under Meshes. The deformed configuration works as a new geometry but with restricted functionality. The Settings window of the deformed configuration indicates which solution it was constructed from. Click the Update button to see the corresponding deformed configuration in the graphics.

Remeshing the Deformed Configuration

Expanding a Deformed Configuration node () shows that a new mesh sequence has been added beneath it. This mesh sequence contains a Size node () and a Reference node () only. The reference node refers to the original mesh sequence. This means that the new mesh sequence uses the same nodes as the original mesh sequence. Build the new mesh sequence by selecting Build All from its context menu or pressing F8. To make changes to the new mesh sequence before building it, right-click Reference 1 and select Expand (). Then the nodes from the original mesh sequence are copied to the new mesh sequence. You can also add and remove nodes in the new mesh sequence. If several meshes are needed on the deformed configuration (for the multigrid solver, for example), you can add an additional mesh sequence by right-clicking Deformed Configuration () and selecting Mesh ().

Continue Solving With the New Mesh

1	In the Settings window for the study step (for example, Study 1>Step1: Time Dependent), use the Mesh list under Mesh Selection to select the new mesh sequence (Mesh 2, for example).

2	Change the Times list under Study Settings or the Parameter value list under Study Extensions to include only the time or parameter corresponding to the deformed configuration plus the remaining times or parameters.

3

Change the initial value to be the last time or parameter of the previous solution. Do this by expanding the Values of Dependent Variables section in the study step settings. Under Initial values of variables solved For, change Settings to User controlled; the change Method to Solution, and locate the previously created solution copy. Then select the appropriate time or parameter value in the Time or Parameter value list. Usually the Automatic setting, which selects the last time or parameter value, suffices. Change the settings under Values of variables not solved for similarly.

4	To solve for remaining times or parameters, right-click Study 1 and select Compute.

Remeshing Several Times

You can remesh several times by iterating the above steps. For each of the solver runs, you get a copy of the solution (Copy 2, Copy 3, Copy 4, and so on) and a corresponding data set (Solution 2, Solution 3, Solution 4, and so on). In the plot group, select one of these data sets for results analysis and visualization.

Alternative Procedure Using Several Studies

The above procedure uses a single study that is modified for each solver run. To recompute the whole sequence of runs, an alternative that uses one study for each run is better. To do that, add a new study after meshing each deformed configuration. The copy solution step is not needed in this case. If the settings are changed in the study or its solver sequence, make these changes also in the new study. For example, the stop condition has to be added.