<div dir="ltr"><div class="gmail_extra"><div class="gmail_quote">On Wed, Apr 5, 2017 at 11:50 AM, Ingo Gaertner <span dir="ltr"><<a href="mailto:ingogaertner.tus@gmail.com" target="_blank">ingogaertner.tus@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div>Hi Jed,<br></div>thank you for your reply. Two followup questions below:<br><div><div><div class="gmail_extra"><br><div class="gmail_quote"><span class="">2017-04-04 22:18 GMT+02:00 Jed Brown <span dir="ltr"><<a href="mailto:jed@jedbrown.org" target="_blank">jed@jedbrown.org</a>></span>:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><span>Ingo Gaertner <<a href="mailto:ingogaertner.tus@gmail.com" target="_blank">ingogaertner.tus@gmail.com</a>> writes:<br>
<br>
> We have never talked about Riemann solvers in our CFD course, and I don't<br>
> understand what's going on in ex11.<br>
> However, if you could answer a few of my questions, you'll give me a good<br>
> start with PETSc. For the simple poisson problem that I am trying to<br>
> implement, I have to discretize div(k grad u) integrated over each FV cell,<br>
> where k is the known diffusivity, and u is the vector to solve for.<br>
<br>
</span>Note that ex11 solves hyperbolic conservation laws, but you are solving<br>
an elliptic equation.<br></blockquote><div><br></div></span><div>I begin to understand. Petscs FVM methods don't provide a FVM library that can be used to implement the FV control volume approach (see Ferziger) for general CFD problems? They are around just because they have been used to tackle one or two specific problems, is this correct?<br></div><div>I thought they could be used similar to the OpenFvm or OpenFoam libraries which seem to solve Poisson, Navier-Stokes, Euler and other problems. If such methods have not been prepared for Petsc, I'll just follow Ferzigers book and start my work on a lower level than I thought would be necessary. More work, more fun :)</div></div></div></div></div></div></blockquote><div><br></div><div>Yes, that is correct.</div><div><br></div><div>As a side note, I think using FV to solve an elliptic equation should be a felony. Continuous FEM is excellent for this, whereas FV needs</div><div>a variety of twisted hacks and is always worse in terms of computation and accuracy. Hyperbolic problems are what FV is designed for</div><div>and I don't think I would ever support it for anything but that.</div><div><br></div><div> Thanks,</div><div><br></div><div> Matt</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div><div><div class="gmail_extra"><div class="gmail_quote"><span class=""><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><span>
> (My second question is more general about the PETSc installation. When I<br>
> configure PETSc with "--prefix=/somewhere --download-triangle<br>
> --download-parmetis" etc., these extra libraries are built correctly during<br>
> the make step, but they are not copied to /somewhere during the "make<br>
> install" step.<br>
<br>
</span>Where are they put during configure?<br></blockquote><div><br></div></span><div>My bad, Petsc installation works as expected. But the build system that I am using is doing something weird. I'll have to find out, what's going wrong there, but it is not related to Petsc.<br><br></div><div>Thank you!<br></div><div>Ingo</div></div><br></div></div></div></div><div id="m_-9031669297911553285DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2"><br> <table style="border-top:1px solid #d3d4de">
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