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<p class="MsoNormal">Hello, <o:p></o:p></p>
<p class="MsoNormal"><span lang="EN-US">I would appreciate an advice on this task, if possible.
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">So far, we use PETSc to ‘couple’ two computations of the same simulation code, in a single MPI run.
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">I simplify but roughly, we have 2 Cartesian domains on which we discretize the same evolution problem.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">These two computations have a common boundary and we want to solve the global problem as if it were a single domain problem.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">We use the ‘ghost cells’ paradigm to handle the boundary conditions.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">At each required step of the time algorithm, we update the values in the ghost cells of both domains.
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Thanks to these exchanges, we can make a global resolution (as if it were a unique domain) by using PETSc : Each domain builds its part of the main operator and its part of the RHS. PETSc solves the global problem and
broadcasts the partial solutions to each domain. <o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">This ‘boundary coupling’ of 2 computations works perfectly well with conforming meshes.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">(we can consider this type of coupling as a domain decomposition process, but instead of cutting a domain in two pieces, we merge two domains together).
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">We are extending this method to the non-conforming case (we use a specific library to make the interpolations/mapping from one grid onto the other).<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">The non-conforming case doesn’t work so far. Our guess is that the error is in the way we fill the data array of PETSc and we keep on working on it.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Would you see a problem we are missing in this extension to the non-conforming situation ? Do you know a similar work we could look at ?
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Thanks for any advice….<o:p></o:p></span></p>
<p class="MsoNormal"><b><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial",sans-serif;color:blue;mso-fareast-language:FR">Pierre</span></b><span lang="EN-US" style="mso-fareast-language:FR"><o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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