<html><head><meta http-equiv="Content-Type" content="text/html; charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><br class=""><div><br class=""><blockquote type="cite" class=""><div class="">Il giorno 24 feb 2020, alle ore 12:24, Matthew Knepley <<a href="mailto:knepley@gmail.com" class="">knepley@gmail.com</a>> ha scritto:</div><br class="Apple-interchange-newline"><div class=""><div dir="ltr" class=""><div dir="ltr" class="">On Mon, Feb 24, 2020 at 5:30 AM Pierpaolo Minelli <<a href="mailto:pierpaolo.minelli@cnr.it" class="">pierpaolo.minelli@cnr.it</a>> wrote:<br class=""></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">Hi,<br class="">
I'm developing a 3D code in Fortran to study the space-time evolution of charged particles within a Cartesian domain.<br class="">
The domain decomposition has been made by me taking into account symmetry and load balancing reasons related to my specific problem.</blockquote><div class=""><br class=""></div><div class="">That may be a problem. DMDA can only decompose itself along straight lines through the domain. Is that how your decomposition looks?</div></div></div></div></blockquote><div><br class=""></div><div>My decomposition at the moment is paractically a 2D decomposition because i have:</div><div><br class=""></div><div>M = 251 (X)</div><div>N = 341 (Y)</div><div>P = 161 (Z)</div><div><br class=""></div><div>and if i use 24 MPI procs, i divided my domain in a 3D Cartesian Topology with:</div><div><br class=""></div><div>m = 4</div><div>n = 6</div><div>p = 1</div><div><br class=""></div><br class=""><blockquote type="cite" class=""><div class=""><div dir="ltr" class=""><div class="gmail_quote"><div class=""> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"> In this first draft, it will remain constant throughout my simulation.<br class="">
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Is there a way, using DMDAs, to solve Poisson's equation, using the domain decomposition above, obtaining as a result the local solution including its ghost cells values?<br class=""></blockquote><div class=""><br class=""></div><div class="">How do you discretize the Poisson equation?</div></div></div></div></blockquote><div><br class=""></div><div>I intend to use a 7 point stencil like that in this example:</div><div><br class=""></div><div><a href="https://www.mcs.anl.gov/petsc/petsc-current/src/ksp/ksp/examples/tutorials/ex22f.F90.html" class="">https://www.mcs.anl.gov/petsc/petsc-current/src/ksp/ksp/examples/tutorials/ex22f.F90.html</a></div><div><br class=""></div><br class=""><blockquote type="cite" class=""><div class=""><div dir="ltr" class=""><div class="gmail_quote"><div class=""><br class=""></div><div class=""> Thanks,</div><div class=""><br class=""></div><div class=""> Matt</div><div class=""> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
As input data at each time-step I know the electric charge density in each local subdomain (RHS), including the ghost cells, even if I don't think they are useful for the calculation of the equation.<br class="">
Matrix coefficients (LHS) and boundary conditions are constant during my simulation.<br class="">
<br class="">
As an output I would need to know the local electrical potential in each local subdomain, including the values of the ghost cells in each dimension(X,Y,Z).<br class="">
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Is there an example that I can use in Fortran to solve this kind of problem?<br class="">
<br class="">
Thanks in advance<br class="">
<br class="">
Pierpaolo Minelli<br class="">
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</blockquote></div><br clear="all" class=""></div></div></blockquote><div><br class=""></div><div><br class=""></div><div>Thanks</div><div>Pierpaolo</div><br class=""><blockquote type="cite" class=""><div class=""><div dir="ltr" class=""><div class=""><br class=""></div>-- <br class=""><div dir="ltr" class="gmail_signature"><div dir="ltr" class=""><div class=""><div dir="ltr" class=""><div class=""><div dir="ltr" class=""><div class="">What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead.<br class="">-- Norbert Wiener</div><div class=""><br class=""></div><div class=""><a href="http://www.cse.buffalo.edu/~knepley/" target="_blank" class="">https://www.cse.buffalo.edu/~knepley/</a><br class=""></div></div></div></div></div></div></div></div>
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