Wrong SaveScalars convective flux

Clearly defined bug reports and their fixes
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Wrong SaveScalars convective flux

Post by cedric.fournier »


First of all I want to thanks all contributors for the great software that elmer is !

I would like to report here a wrong calculation of the convective flux accross a surface boundary obtained with the SaveSclars model. Here you can found a zip file containing the mesh, the sif file, log file and also the vtu results :
https://drive.google.com/file/d/1ZoH264 ... sp=sharing
  • elmer version : Version: 9.0 (Rev: Release, Compiled: 2023-11-30)
  • Convective flux over boundary 3 is correct : 1.273442854802E-003 (third column of _air_flow.result file), 1.2686e-3 obtained with ParaView SurfaceFlow
  • Convective flux over boundary 1 and 2 are incorrect : 6.764948413966E-017 and 1.249834425623E-016 (first and second column of _air_flow.result file or _air_flow1.result of _air_flow2.result), 6.31e-4 and 6.38e-4 obtained with ParaView SurfaceFlow
So, what I could say is
  • The velocity field obtained is correct, but the computed convective flux over boundary 1 and 2 is not (~0)
  • The computed convective flux over boundary 3 is correct
  • I have tired severals variants (Solver 6, 7 and 8) (adding a solver only for bc1 and bc2, using a solver for bc1, bc2 and bc3)

  • A coarse mesh was used to reduce computing time and size
  • I know that the heat equation does not converge (due to coarse mesh), but this does not matter for the convective flux computed with velocity
Thank you for you support.

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