Re: [deal.II] Monolithic FSI: Problem with periodic-like constraints and flux sparsity pattern

[Wolfgang Bangerth]

Hi Jason,

my apologies for only now getting to this :-(


> I have been developing a fluid-structure interaction (FSI) solver using
> deali.II (somewhat similar to example step-46). I've run into an issue
> with the application of some constraints when attempting a monolithic
> coupling strategy.
> [...]

Interesting. You are hitting a case where we try to do something with
one block of a block matrix. It turns out that the last few rows of this
block are empty and so when we are asking for the address of the first
entry of one of these rows it turns out that it is beyond the end of the
allocated array.

Once understood, the issue is easy to fix and I've just committed the
change along with your testcase -- many thanks for cutting it down to
such manageable size! The patch is also attached.

I haven't looked at the second case you sent. Can you verify that it
also works now?

Best
W.

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Wolfgang Bangerth email: bang...@math.tamu.edu
www: http://www.math.tamu.edu/~bangerth/

[Jason Sheldon]

Hi Wolfgang,

Thanks for taking a look into this.  I had discovered that I could get around the problem with a constraints.condense call on the sparsity pattern, but I was concerned the underlying issue might still be present. 

Your patch does seem to solve the problem in the second case as well.

Jason

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