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<p>Hi Martin,</p>
<p>I'll try to set up a small example.</p>
<p>The weird thing is that I have 2k elements in my coarse grid and this problem occurs for only 1 intersection. That's why I would like to see how the intersection is built, in order to understand if my code wrongly changes that intersection object.</p>
<p>Thanks.</p>
<p><br>
</p>
<p>Marco</p>
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<div id="x_divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" color="#000000" style="font-size:11pt"><b>Da:</b> Martin Nolte <nolte@mathematik.uni-freiburg.de><br>
<b>Inviato:</b> mercoledì 25 maggio 2016 17.47<br>
<b>A:</b> Dune<br>
<b>Oggetto:</b> Re: [Dune] Intersection area and corners</font>
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<div class="PlainText">Hi Marco,<br>
<br>
the intersection of GeometryGrid is based on the intersection of the host<br>
grid. Then, you use the geometryInInside and the element geometry (of the<br>
inside element) to build the global geometry of the intersection. So, in a<br>
conforming situation, the corners of the intersection should be a subset of<br>
the corners of the inside element.<br>
<br>
Therefore, I consider your question a bug. Can you provide a small example?<br>
<br>
Best,<br>
<br>
Martin<br>
<br>
On 05/25/2016 03:59 PM, Marco Cisternino wrote:<br>
> Thank you Martin for your quick reply.<br>
> <br>
> No, for the configuration I'm debugging I'm not dealing with non-conforming<br>
> elements. That's why I cannot really understand why intersection and element<br>
> are not coherent.<br>
> <br>
> How the intersection is built? I could look in the constructor to see why its<br>
> corners are not among the element corners.<br>
> <br>
> Thanks again<br>
> <br>
> <br>
> Marco<br>
> <br>
> <br>
> <br>
> <br>
> ------------------------------------------------------------------------------<br>
> *Da:* Martin Nolte <nolte@mathematik.uni-freiburg.de><br>
> *Inviato:* mercoledì 25 maggio 2016 11.00<br>
> *A:* Dune<br>
> *Oggetto:* Re: [Dune] Intersection area and corners<br>
> <br>
> Hi Marco,<br>
> <br>
> I am not sure whether I get your question correctly. You seem to be comparing<br>
> the geometry of the inside element to the geometry of the intersection.<br>
> <br>
> This is only reasonable, if the intersection is conforming. Otherwise I expect<br>
> the corners to be different. Is it possible, that your intersection is<br>
> non-conforming?<br>
> <br>
> Please note the using GeometryGrid with non-conforming grid views is a bit<br>
> problematic. Basically you are creating a first order Lagrange function over a<br>
> non-conforming grid. If you don't constrain hanging nodes, the position of a<br>
> hanging node might not be on the edge of the bigger element but slightly moved.<br>
> <br>
> You might also want to have a look at the following merge request:<br>
> <br>
> <a href="https://gitlab.dune-project.org/core/dune-grid/merge_requests/60" id="LPlnk486277">
https://gitlab.dune-project.org/core/dune-grid/merge_requests/60</a>
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<a id="LPUrlAnchor_14642645768760.5100894618610565" href="https://gitlab.dune-project.org/core/dune-grid/merge_requests/60" target="_blank" style="text-decoration: none;">Bugfix/geometrygrid various (!60) · Merge Requests · Core Modules / dune-grid</a></div>
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Grid Interface and Implementations</div>
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<br>
> <<a href="https://gitlab.dune-project.org/core/dune-grid/merge_requests/60">https://gitlab.dune-project.org/core/dune-grid/merge_requests/60</a>><br>
> <br>
> Bugfix/geometrygrid various (!60) · Merge Requests · Core Modules / dune-grid<br>
> <<a href="https://gitlab.dune-project.org/core/dune-grid/merge_requests/60">https://gitlab.dune-project.org/core/dune-grid/merge_requests/60</a>><br>
> gitlab.dune-project.org<br>
> Grid Interface and Implementations<br>
> <br>
> <br>
> <br>
> <br>
> It deals with normals in non-conforming grids, which might also be buggy in<br>
> DUNE 2.3.<br>
> <br>
> Best,<br>
> <br>
> Martin<br>
> <br>
> On 05/25/2016 10:44 AM, Marco Cisternino wrote:<br>
>> Good morning,<br>
>> I have a problem with one intersection in my dune application.<br>
>> The area I get is not what I expect.<br>
>> So I tried to look inside the Intersection object using gdb<br>
>> It is important to say that my grid is a GeometryGrid with a DiscreteFunction to parametrize the elements.<br>
>> <br>
>> If I look at these two things:<br>
>> <br>
>> - *(in.real.insideGeo_.mapping_)<br>
>> - *(iGeo.realGeometry.mapping_)<br>
>> <br>
>> where the in variable type is <br>
>> GeometryGrid::LeafGridView::IntersectionIterator::Intersection<br>
>> and iGeo is <br>
>> GeometryGrid::LeafGridView::IntersectionIterator::Intersection::Geometry<br>
>> <br>
>> I see different corners stored in. I mean two of the 4 corners given by *(iGeo.realGeometry.mapping_) are different from the two correspondant corners given by *(in.real.insideGeo_.mapping_). All the other corners are the same.<br>
>> <br>
>> If I compute the intersection area using corners given by *(in.real.insideGeo_.mapping_), I get the right area. On the other hand, if I compute the intersection area using the corners given by *(iGeo.realGeometry.mapping_), the area is wrong.<br>
>> <br>
>> I want to specify that the corners given by *(in.real.insideGeo_.mapping_) are the same I get using e.geometry().corners(i) where e is of type<br>
>> GeometryGrid::LeafGridView::template Codim<0>::template Partition<Dune::InteriorBorder_Partition>::Iterator::Entity<br>
>> <br>
>> Could anyone help me please? Am I doing something wrong?<br>
>> Ask for more details if you need.<br>
>> <br>
>> I'm using DUNE 2.3 with ALUGrid 1.52. I know it is old, but at the moment I cannot migrate to the new Dune releases.<br>
>> <br>
>> Thanks a lot!<br>
>> <br>
>> Marco<br>
>> <br>
>> _______________________________________________<br>
>> Dune mailing list<br>
>> Dune@dune-project.org<br>
>> <a href="http://lists.dune-project.org/mailman/listinfo/dune">http://lists.dune-project.org/mailman/listinfo/dune</a><br>
>> <br>
> <br>
> -- <br>
> Dr. Martin Nolte <nolte@mathematik.uni-freiburg.de><br>
> <br>
> Universität Freiburg phone: +49-761-203-5630<br>
> Abteilung für angewandte Mathematik fax: +49-761-203-5632<br>
> Hermann-Herder-Straße 10<br>
> 79104 Freiburg, Germany<br>
> <br>
> <br>
<br>
-- <br>
Dr. Martin Nolte <nolte@mathematik.uni-freiburg.de><br>
<br>
Universität Freiburg phone: +49-761-203-5630<br>
Abteilung für angewandte Mathematik fax: +49-761-203-5632<br>
Hermann-Herder-Straße 10<br>
79104 Freiburg, Germany<br>
<br>
<br>
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