POLYFLOW - Why does the free surface exhibit some wiggles, in saw teeth?
When running a 2D free surface flow, it may happen that the calculation converges, but the free surface may exhibit wiggles like a saw with one or more teeth. In axisymmetric situations, radial coordinate of nodes may become negative; it may receive the value -2r instead of r. At some moment, the solver blows up. What is happening?
So far, this has been observed very seldomly, for a given mesh.
Possible remedies are:
- use double precision (keyword DBUFFER in the .p3rc file),
- consider a mesh decomposition in 2 or 4 subparts.
- use upwinding for the free surface