On 1/18/20 5:02 PM, David Eaton wrote:
> I just use tecplot directly visualize the results. The vorticity contour from 
> my simple code is continuous, and the results from deal.II is discontinuous 
> (without L2 projection).

Ah, I think that is it. Bruno was already on the right track.

I bet that your own code outputs the solution in a way that assigns only one 
value to each node, and tecplot then computes a discontinuous gradient that it 
averages at each node again from the adjacent cells. On the other hand, 
deal.II outputs the value at each node as many times as there are adjacent 
cells, and tecplot doesn't know how to average in that case.

In other words, what tecplot is doing *internally* is to do a projection (or 
some other averaging operation) so that it *shows* you a continuous gradient 
or vorticity field. But this is just another case where what you *see* is not 
actually what it *is*. The gradient is discontinuous, regardless of what 
tecplot shows you.

Best
  W.

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Wolfgang Bangerth          email:                 bange...@colostate.edu
                            www: http://www.math.colostate.edu/~bangerth/

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