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<p>So the difference between the two types is in <tt>DMPlexGetFaceFields</tt>
: the upwind just takes the cell averaged (or cell centerd)
states, and the least-squares use the gradient to reconstruct the
states ?</p>
<p>Thanks<br>
</p>
<p>Pierre<br>
</p>
<br>
<div class="moz-cite-prefix">On 18/09/20 12:24, Matthew Knepley
wrote:<br>
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cite="mid:CAMYG4GmWGiMzMSJ6bKE1q3hv54uUnnO=N44FsdLDVGEtwguuXg@mail.gmail.com">
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<div dir="ltr">On Fri, Sep 18, 2020 at 4:01 AM Pierre Seize <<a
href="mailto:Pierre.Seize@onera.fr" moz-do-not-send="true">Pierre.Seize@onera.fr</a>>
wrote:<br>
</div>
<div class="gmail_quote">
<blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left:1px solid
rgb(204,204,204);padding-left:1ex">Hello,<br>
<br>
I do not understand what are the two available types for the
PetscFV <br>
object : "upwind" and "leastsquares", because to me those
two properties <br>
describe different parts of the Finite Volume formulation.
Could someone <br>
explain, or give me some references ?<br>
</blockquote>
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<div>Sure. PetscFV is mostly an exercise for me to determine
if the meshing and data layout</div>
<div>infrastructure below can support finite volume methods,
so the FV methods that it does support</div>
<div>are rather rudimentary. My understanding of FV is quite
limited. "upwind" is just the naive, first</div>
<div>order FV method with pointwise Riemann solves for each
local face. I called it upwind since we</div>
<div>just update the state with the upwind data. I guess I
could have called it "gudonov" as well. The</div>
<div>"leastsquares" uses a least-squares reconstruction of the
state over cell+neighboring cells (closure</div>
<div>of the star of the faces) to try and achieve second-order
where possible. I guess I could have called</div>
<div>this "reconstructed".</div>
<div><br>
</div>
<div> Thanks,</div>
<div><br>
</div>
<div> Matt</div>
<div> </div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px
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rgb(204,204,204);padding-left:1ex">
Thank you<br>
<br>
<br>
Pierre Seize<br>
<br>
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-- <br>
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<div>What most experimenters take for granted before
they begin their experiments is infinitely more
interesting than any results to which their
experiments lead.<br>
-- Norbert Wiener</div>
<div><br>
</div>
<div><a
href="http://www.cse.buffalo.edu/%7Eknepley/"
target="_blank" moz-do-not-send="true">https://www.cse.buffalo.edu/~knepley/</a><br>
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