[Einstein Toolkit] #1221: Reduction weight anomaly when using zero CoordBase::boundary_shiftout_*

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Einstein Toolkit

16 Jan 2013 16 Jan '13

3:08 a.m.

#1221: Reduction weight anomaly when using zero CoordBase::boundary_shiftout_* ------------------------+--------------------------------------------------- Reporter: bentivegna | Owner: eschnett Type: defect | Status: new Priority: minor | Milestone: Component: Carpet | Version: development version Keywords: | ------------------------+--------------------------------------------------- When using a refinement level that covers the entire grid, and setting the CoordBase::boundary_shiftout_* parameters to zero, the following warning appears:

INFO (CarpetReduce): Simulation domain volume: 8000 INFO (CarpetReduce): Additional excised volume: 0 INFO (CarpetReduce): Reduction weight sum: 9141 WARNING level 1 in thorn CarpetReduce processor 0 host socket.local (line 137 of /Users/bennie/CactusTrees/TrueAMR/arrangements/Carpet/CarpetReduce/src/mask_test.c): -> Simulation domain volume and reduction weight sum differ

This can be reproduced using the attached parameter file. The problem seems to arise at the boundaries of the restricted region: I would expect the coarse grid to carry zero reduction weight everywhere (as it does if the shiftout is one), but the boundaries have a non-zero weight instead, which leads to double counting, and hence the difference between domain volume and weight sum.

-- Ticket URL: https://trac.einsteintoolkit.org/ticket/1221 Einstein Toolkit http://einsteintoolkit.org The Einstein Toolkit

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Einstein Toolkit

16 Jan 16 Jan

8:53 a.m.

#1221: Reduction weight anomaly when using zero CoordBase::boundary_shiftout_* -------------------------+-------------------------------------------------- Reporter: bentivegna | Owner: eschnett Type: defect | Status: new Priority: minor | Milestone: Component: Carpet | Version: development version Resolution: | Keywords: -------------------------+--------------------------------------------------

Comment (by eschnett):

I believe this issue is unrelated to #1222. Looking at the weights, I see the effect you describe: coarse grid outer boundaries have non-zero weight where fine grid boundaries also have non-zero weight. This seems to be an error in setting up the boundary weights, which apparently doesn't take refined grids correctly into account.

-- Ticket URL: https://trac.einsteintoolkit.org/ticket/1221#comment:1 Einstein Toolkit http://einsteintoolkit.org The Einstein Toolkit

Einstein Toolkit

9:26 a.m.

Comment (by eschnett):

After investigating, the reason for this problem seems to be that the regions do not "wrap around". That is, a fine grid abutting the right boundary does not influence the left boundary of the domain. To remedy this, one would need to teach the weight setup explicitly about periodic boundaries.

Can you switch to cell centred grids? Would this work for you? These should not have this problems.

-- Ticket URL: https://trac.einsteintoolkit.org/ticket/1221#comment:2 Einstein Toolkit http://einsteintoolkit.org The Einstein Toolkit

Einstein Toolkit

9:37 a.m.

Comment (by eschnett):

My last comment is wrong since periodic boundaries are not involved.

-- Ticket URL: https://trac.einsteintoolkit.org/ticket/1221#comment:3 Einstein Toolkit http://einsteintoolkit.org The Einstein Toolkit

Einstein Toolkit

10:51 a.m.

Comment (by bentivegna):

Yes, this problem occurs whether periodic boundaries are involved or not.

I'm not sure cell-centred grids would work for me (possibly yes). It would be nice if the issue with the vertex-centred ones was solved though. Can I help in any way?

-- Ticket URL: https://trac.einsteintoolkit.org/ticket/1221#comment:4 Einstein Toolkit http://einsteintoolkit.org The Einstein Toolkit

Einstein Toolkit

11:19 a.m.

Comment (by eschnett):

I believe now that the issue is simply that fine grid boundaries not taken into account when setting the weight for coarse grid boundaries. Thus coarse grid boundaries always have non-zero weight. This is probably a left-over assumption from when the fine grid was never near a boundary.

If that is the case, then addressing it will be non-trivial.

-- Ticket URL: https://trac.einsteintoolkit.org/ticket/1221#comment:5 Einstein Toolkit http://einsteintoolkit.org The Einstein Toolkit

Einstein Toolkit

17 Jan 17 Jan

2:32 a.m.

Comment (by bentivegna):

I see. An observation is that the behavior is completely correct when using a shiftout of one (in that case all the coarse grid points are masked out), so perhaps it's not so hard to find out where this parameter makes a difference and fix it. I briefly attempted doing this before opening the ticket, but with no success. I'll give it another try.

-- Ticket URL: https://trac.einsteintoolkit.org/ticket/1221#comment:6 Einstein Toolkit http://einsteintoolkit.org The Einstein Toolkit

Einstein Toolkit

11:25 a.m.

Comment (by eschnett):

I'm afraid it is not simple. With a shiftout of 1, this issue does not arise. If my reading of the code is correct, then we need to introduce a completely new mechanism for this, starting in CarpetLib/src/dh.cc.

-- Ticket URL: https://trac.einsteintoolkit.org/ticket/1221#comment:7 Einstein Toolkit http://einsteintoolkit.org The Einstein Toolkit

Einstein Toolkit

12:57 p.m.

Comment (by bentivegna):

OK. I'll consider switching to cell-centred grids, but I may return on this later.

-- Ticket URL: https://trac.einsteintoolkit.org/ticket/1221#comment:8 Einstein Toolkit http://einsteintoolkit.org The Einstein Toolkit

Einstein Toolkit

8 Apr 8 Apr

10:50 a.m.

#1221: Reduction weight anomaly when using zero CoordBase::boundary_shiftout_* -------------------------+-------------------------------------------------- Reporter: bentivegna | Owner: eschnett Type: defect | Status: new Priority: minor | Milestone: ET_2013_05 Component: Carpet | Version: development version Resolution: | Keywords: -------------------------+-------------------------------------------------- Changes (by eschnett):

* milestone: => ET_2013_05

-- Ticket URL: https://trac.einsteintoolkit.org/ticket/1221#comment:9 Einstein Toolkit http://einsteintoolkit.org The Einstein Toolkit

Einstein Toolkit

25 Apr 25 Apr

10:24 a.m.

#1221: Reduction weight anomaly when using zero CoordBase::boundary_shiftout_* -------------------------+-------------------------------------------------- Reporter: bentivegna | Owner: eschnett Type: defect | Status: new Priority: minor | Milestone: ET_2013_05 Component: Carpet | Version: development version Resolution: | Keywords: -------------------------+--------------------------------------------------

Comment (by knarf):

Has this a chance of getting fixed soon?

-- Ticket URL: https://trac.einsteintoolkit.org/ticket/1221#comment:10 Einstein Toolkit http://einsteintoolkit.org The Einstein Toolkit

Einstein Toolkit

12:59 p.m.

#1221: Reduction weight anomaly when using zero CoordBase::boundary_shiftout_* -------------------------+-------------------------------------------------- Reporter: bentivegna | Owner: eschnett Type: defect | Status: new Priority: minor | Milestone: ET_2013_05 Component: Carpet | Version: development version Resolution: | Keywords: -------------------------+--------------------------------------------------

Comment (by eschnett):

Eloisa: Is this still an issue (if you use cell-centred grids)?

Frank: No, this requires a non-trivial calculation to be corrected. This involves a special case that only occurs for periodic boundaries (vertex centring with boundary_shiftout=0).

-- Ticket URL: https://trac.einsteintoolkit.org/ticket/1221#comment:11 Einstein Toolkit http://einsteintoolkit.org The Einstein Toolkit

Einstein Toolkit

26 Apr 26 Apr

3:04 a.m.

#1221: Reduction weight anomaly when using zero CoordBase::boundary_shiftout_* -------------------------+-------------------------------------------------- Reporter: bentivegna | Owner: eschnett Type: defect | Status: new Priority: minor | Milestone: ET_2013_05 Component: Carpet | Version: development version Resolution: | Keywords: -------------------------+--------------------------------------------------

Comment (by bentivegna):

I haven't tried cell-centred grids yet. In any case, I would leave this ticket open as a low-priority enhancement request, rather than closing it and forgetting about the fact that this setup is not supported.

-- Ticket URL: https://trac.einsteintoolkit.org/ticket/1221#comment:12 Einstein Toolkit http://einsteintoolkit.org The Einstein Toolkit

Einstein Toolkit

17 May 17 May

2:31 p.m.

* milestone: ET_2013_05 =>

Comment:

Unlikely to be fixed so late and still get tested.

-- Ticket URL: https://trac.einsteintoolkit.org/ticket/1221#comment:13 Einstein Toolkit http://einsteintoolkit.org The Einstein Toolkit

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