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<p style="margin-top:0;margin-bottom:0">Hi Saikat,</p>
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<p style="margin-top:0;margin-bottom:0">How large is your finite-difference look up table?</p>
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</p>
<p style="margin-top:0;margin-bottom:0">(1 million points? 1 billion? 1000?)</p>
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</p>
<p style="margin-top:0;margin-bottom:0">If it's not too large you can just copy it onto each mpi rank</p>
<p style="margin-top:0;margin-bottom:0">and then call your own serial interpolation routine for each</p>
<p style="margin-top:0;margin-bottom:0">SEM point, x,y,z, and store the results into an array in a </p>
<p style="margin-top:0;margin-bottom:0">common block that you can then reference in users</p>
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</p>
<p style="margin-top:0;margin-bottom:0">Presumably you'd have to do this interpolation only one</p>
<p style="margin-top:0;margin-bottom:0">time and then de-reference the values from the common</p>
<p style="margin-top:0;margin-bottom:0">block on each time step with fairly low overhead.</p>
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<p style="margin-top:0;margin-bottom:0">Paul</p>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> Nek5000-users <nek5000-users-bounces@lists.mcs.anl.gov> on behalf of nek5000-users@lists.mcs.anl.gov <nek5000-users@lists.mcs.anl.gov><br>
<b>Sent:</b> Wednesday, May 30, 2018 2:42:14 PM<br>
<b>To:</b> nek5000-users@lists.mcs.anl.gov<br>
<b>Subject:</b> Re: [Nek5000-users] Using Cartesian grid lookup table in Nekton</font>
<div> </div>
</div>
<div class="BodyFragment"><font size="2"><span style="font-size:11pt;">
<div class="PlainText">There is nothing spectral element specific here. You could do e.g. a trilinear interpolation but that's something you have to code yourself.
<br>
<br>
-----Original message-----<br>
> From:nek5000-users@lists.mcs.anl.gov <nek5000-users@lists.mcs.anl.gov><br>
> Sent: Wednesday 30th May 2018 21:26<br>
> To: nek5000-users <nek5000-users@lists.mcs.anl.gov><br>
> Subject: Re: [Nek5000-users] Using Cartesian grid lookup table in Nekton<br>
> <br>
> The question is how to read in a discrete data set defined in a finite difference grid in ffx or forcing in the .usr file. It seems like there will be some sort of interpolation to the spectral element grid. So yes, that is my question.<br>
> <br>
> Thank you,<br>
> Saikat<br>
> <br clear="all" />Saikat Mukherjee,<br>
> PhD Student,<br>
> Paul Research Group - <a href="http://www.me.vt.edu/mpaul/">http://www.me.vt.edu/mpaul/</a> <<a href="http://www.me.vt.edu/mpaul/">http://www.me.vt.edu/mpaul/</a>><br>
> Engineering Science and Mechanics,<br>
> Virginia Tech.<br>
> <br>
> On Wed, May 30, 2018 at 2:48 PM, <nek5000-users@lists.mcs.anl.gov <<a href="mailto:nek5000-users@lists.mcs.anl.gov">mailto:nek5000-users@lists.mcs.anl.gov</a>>> wrote:<br>
> What’s your question? How to do the interpolation in your function f?<br>
> <br>
> On 30 May 2018, at 20:17, "nek5000-users@lists.mcs.anl.gov <<a href="mailto:nek5000-users@lists.mcs.anl.gov">mailto:nek5000-users@lists.mcs.anl.gov</a>>" <nek5000-users@lists.mcs.anl.gov <<a href="mailto:nek5000-users@lists.mcs.anl.gov">mailto:nek5000-users@lists.mcs.anl.gov</a>>>
wrote:<br>
> <br>
> Hi,<br>
> <br>
> Thanks for the reply. My problem is f is given as a discrete data set described in finite difference grid. I want to interpolate this to ffx like you said in my .usr file. Would like to know how to proceed.<br>
> <br>
> Thanks,<br>
> Saikat<br>
> <br clear="all" />Saikat Mukherjee,<br>
> PhD Student,<br>
> Paul Research Group - <a href="http://www.me.vt.edu/mpaul/">http://www.me.vt.edu/mpaul/</a> <<a href="http://www.me.vt.edu/mpaul/">http://www.me.vt.edu/mpaul/</a>><br>
> Engineering Science and Mechanics,<br>
> Virginia Tech.<br>
> <br>
> On Wed, May 30, 2018 at 1:36 PM, <nek5000-users@lists.mcs.anl.gov <<a href="mailto:nek5000-users@lists.mcs.anl.gov">mailto:nek5000-users@lists.mcs.anl.gov</a>>> wrote:<br>
> Lets consider <br>
> <br>
> ffx = f(x,y,z)<br>
> <br>
> here f is an user function (something you have to provide) which get evaluated at x,y,z (your grid points). Interpolation is required if f is given by a discrete data set.
<br>
> <br>
> hth<br>
> <br>
> <br>
> -----Original message-----<br>
> > From:nek5000-users@lists.mcs.anl.gov <<a href="mailto:From%3Anek5000-users@lists.mcs.anl.gov">mailto:From%3Anek5000-users@lists.mcs.anl.gov</a>> <nek5000-users@lists.mcs.anl.gov <<a href="mailto:nek5000-users@lists.mcs.anl.gov">mailto:nek5000-users@lists.mcs.anl.gov</a>>><br>
> > Sent: Wednesday 30th May 2018 19:19<br>
> > To: nek5000-users <nek5000-users@lists.mcs.anl.gov <<a href="mailto:nek5000-users@lists.mcs.anl.gov">mailto:nek5000-users@lists.mcs.anl.gov</a>>><br>
> > Subject: Re: [Nek5000-users] Using Cartesian grid lookup table in Nekton<br>
> > <br>
> > Hi,<br>
> > <br>
> > Thanks for the reply. The look up table is in a finite difference grid. Are you saying I can still feed it to the .usr file and it should be fine?<br>
> > <br>
> > Thanks,<br>
> > Saikat<br>
> > <br clear="all" />Saikat Mukherjee,<br>
> > PhD Student,<br>
> > Paul Research Group - <a href="http://www.me.vt.edu/mpaul/">http://www.me.vt.edu/mpaul/</a> <<a href="http://www.me.vt.edu/mpaul/">http://www.me.vt.edu/mpaul/</a>> <<a href=""></a>http://www.me.vt.edu/mpaul/ <<a href="http://www.me.vt.edu/mpaul/">http://www.me.vt.edu/mpaul/</a>>><br>
> > Engineering Science and Mechanics,<br>
> > Virginia Tech.<br>
> > <br>
> > On Sat, May 26, 2018 at 10:54 PM, <nek5000-users@lists.mcs.anl.gov <<a href="mailto:nek5000-users@lists.mcs.anl.gov">mailto:nek5000-users@lists.mcs.anl.gov</a>> <<a href=""></a>mailto:nek5000-users@lists.mcs.anl.gov <<a href="mailto:nek5000-users@lists.mcs.anl.gov">mailto:nek5000-users@lists.mcs.anl.gov</a>>>>
wrote:<br>
> > Hi Saikat,<br>
> > <br>
> > You can always do the reading from the look up table from .usr file, at once then feed the data to your ffx ffy and ffz through a common block.<br>
> > <br>
> > On Thu, May 24, 2018 at 10:55 PM, <nek5000-users@lists.mcs.anl.gov <<a href="mailto:nek5000-users@lists.mcs.anl.gov">mailto:nek5000-users@lists.mcs.anl.gov</a>> <<a href=""></a>mailto:nek5000-users@lists.mcs.anl.gov <<a href="mailto:nek5000-users@lists.mcs.anl.gov">mailto:nek5000-users@lists.mcs.anl.gov</a>>>>
wrote:<br>
> > Hey all,<br>
> > <br>
> > Just following up on the query. Would appreciate any input.<br>
> > <br>
> > Thanks,<br>
> > Saikat<br>
> > <br clear="all" />Saikat Mukherjee,<br>
> > PhD Student,<br>
> > Paul Research Group - <a href="http://www.me.vt.edu/mpaul/">http://www.me.vt.edu/mpaul/</a> <<a href="http://www.me.vt.edu/mpaul/">http://www.me.vt.edu/mpaul/</a>> <<a href=""></a>http://www.me.vt.edu/mpaul/ <<a href="http://www.me.vt.edu/mpaul/">http://www.me.vt.edu/mpaul/</a>>><br>
> > Engineering Science and Mechanics,<br>
> > Virginia Tech.<br>
> > <br>
> > On Tue, May 22, 2018 at 4:47 PM, Saikat Mukherjee <msaikat6@vt.edu <<a href="mailto:msaikat6@vt.edu">mailto:msaikat6@vt.edu</a>> <<a href=""></a>mailto:msaikat6@vt.edu <<a href="mailto:msaikat6@vt.edu">mailto:msaikat6@vt.edu</a>>>> wrote:<br>
> > Hey Neks,<br>
> > <br>
> > I have a forcing function which is in the form of a look up table in X-Y cartesian grid. I would like to use this forcing function in the 2-D fluid momentum equation that Nekton solves. Is there a way to do this in the .usr file or elsewhere?<br>
> > <br>
> > Thanks,<br>
> > Saikat<br>
> > <br>
> > <br>
> > <br clear="all" />Saikat Mukherjee,<br>
> > PhD Student,<br>
> > Paul Research Group - <a href="http://www.me.vt.edu/mpaul/">http://www.me.vt.edu/mpaul/</a> <<a href="http://www.me.vt.edu/mpaul/">http://www.me.vt.edu/mpaul/</a>> <<a href=""></a>http://www.me.vt.edu/mpaul/ <<a href="http://www.me.vt.edu/mpaul/">http://www.me.vt.edu/mpaul/</a>>><br>
> > Engineering Science and Mechanics,<br>
> > Virginia Tech.<br>
> > <br>
> > <br>
> > _______________________________________________<br>
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> > Nek5000-users@lists.mcs.anl.gov <<a href="mailto:Nek5000-users@lists.mcs.anl.gov">mailto:Nek5000-users@lists.mcs.anl.gov</a>> <<a href=""></a>mailto:Nek5000-users@lists.mcs.anl.gov <<a href="mailto:Nek5000-users@lists.mcs.anl.gov">mailto:Nek5000-users@lists.mcs.anl.gov</a>>><br>
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