Possibility to visualize curved boundaries

[DanielDoehring]

I am not sure how this could be done, but it would be nice to visualize beyond polygonial boundaries.

For one of the freestream tests (https://github.com/trixi-framework/Trixi.jl/blob/main/examples/p4est_2d_dgsem/elixir_euler_free_stream.jl) an analytic mapping function is given which results in a truly curved boundary. The visualization with paraview however, cannot represent this curved boundary accurately:

You see some holes in the mesh, which are obviously not there in the mesh used for solving.

[efaulhaber]

Did you increase the nonlinear subdivision level in ParaView? It should be possible to show curved boundaries, although not always perfectly.

[DanielDoehring]

I was not aware of this option. Maybe we can add it somewhere in the Trixi2Vtk docs?