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marcfehling / hpbox

Sandbox for hp-adaptive methods
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Stokes Matrixbased: Adding a dummy element leads to different refinement behavior #13

Open marcfehling opened 3 months ago

marcfehling commented 3 months ago

After 2ea5eb1 which added a dummy element for the matrixbased Stokes implementation, I noticed a different hp-refinement behavior in the 3D ypipe test. Interestingly, the 2D Kovasznay test remains unaffected.

Try to...

  1. ...recreate error with pure h-refinement to rule out errors in the SmoothnessEstimator
  2. ...then compare the number of cells refined to rule out errors in the KellyErrorEstimator
  3. ...check matrix/solution norms

Also investigate any effects on the solver performance. The AMG version of both matrixbased and matrixfree implementations should produce the same result.

Test: $ ctest -V -R ypipe_dealiitrilinos.prm

New behavior:

Cycle 0:
   Number of global levels:      1
   Number of active cells:       72
   Max active FE index in use  : 1
   Frequencies of poly. degrees: 2:72
   Number of degrees of freedom: 2420
   Solved in 32 iterations.

Cycle 1:
   Number of global levels:      2
   Number of active cells:       156
   Max active FE index in use  : 2
   Frequencies of poly. degrees: 2:144 3:12
   Number of degrees of freedom: 7467
   Solved in 41 iterations.

Cycle 2:
   Number of global levels:      3
   Number of active cells:       317
   Max active FE index in use  : 2
   Frequencies of poly. degrees: 2:226 3:91
   Number of degrees of freedom: 20559
   Solved in 50 iterations.

Old behavior:

Cycle 0:
   Number of global levels:      1
   Number of active cells:       72
   Max active FE index in use  : 0
   Frequencies of poly. degrees: 2:72
   Number of degrees of freedom: 2420
   Solved in 32 iterations.

Cycle 1:
   Number of global levels:      2
   Number of active cells:       149
   Max active FE index in use  : 1
   Frequencies of poly. degrees: 2:139 3:10
   Number of degrees of freedom: 7129
   Solved in 40 iterations.

Cycle 2:
   Number of global levels:      3
   Number of active cells:       303
   Max active FE index in use  : 1
   Frequencies of poly. degrees: 2:222 3:81
   Number of degrees of freedom: 19246
   Solved in 53 iterations.