4.4. Specifying Criteria-Checking Frequency

Specify the frequency at which criteria for each component are checked during solution (NLADAPTIVE,,ON).

VAL1 controls the checking frequency:

  • If VAL1 > 0, the program checks the nonlinear mesh adaptivity criteria every VAL1 substeps.

  • If VAL1 < 0, the program checks VAL1 number of times distributed evenly throughout the load step or defined time interval.

Default: VAL1 = -1

For mesh-quality-based criteria, it is good practice to check the criteria at every two substeps. To exploit the accuracy property of the hex-dom meshes, however, you can control the first time point and the range for checking via VAL2 and VAL3 arguments.

Criteria-checking does not guarantee that remeshing occurs at a given substep. A new mesh is generated for the component only if any element meets the criteria assigned to it.

Remeshing Points

Because nonlinear adaptivity does not control the substep length (solution points), it cannot accurately control the number of splitting or remeshing points.

For frequency checking (NLADAPTIVE,,ON,,,-n,StartTime,EndTime), remeshing may not occur between StartTime and EndTime if no solution point falls between them. Fewer remeshings may occur, even fewer than n, if the number of solution points is less than n. In many cases, just the first remeshing (from hex-dom to tetrahedral element) may be the only possible mesh-change operation for a given component.

Conversely, the program may remesh n + 1 times if the solution has one point close to StartTime and another close to EndTime. In most cases, this behavior affects the pure tetrahedral elements after the hex-to-tet remeshing has occurred in the first remeshing.