Unable to visualise high order polynomial variation in ParaView

[vachanpo...@gmail.com]

Dear all,

I have a working code that outputs pvtu/vtu files for visualisation.

I have read the wiki page for writing and visualising high order output. Currently, I only have straight-edge quadrilaterals so I the only change I have made to my code is to update VtkFlags and set them in the DataOut object (as below). Please correct me if I am missing anything here.

DataOutBase::VtkFlags flags;
flags.write_higher_order_cells = true;
data_out.set_flags(flags);

However, the output of this modified code still produces linear variation when visualised. I have also set the Nonlinear Subdivision Level in paraview accordingly. But is seems to produce no change.

What am I missing?

Thanking in anticipation

Vachan

[luca.heltai]

Did you call

data_out.build_patches(mapping, subdivisions,DataOut<dim>::curved_inner_cells);

with subdivisions > 1?

L.

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[Timo Heister]

One thing that might not be obvious is that it is not enough to have a manifold id for boundary faces. You need to assign a manifold to the cells as well.

[vachanpo...@gmail.com]

Did you call

data_out.build_patches(mapping, subdivisions,DataOut<dim>::curved_inner_cells);

with subdivisions > 1?

Thanks a lot. I was missing this. Since my mesh has only straight edges, I am instead calling

data_out.build_patches(fe.order);