Hi Alireza,<br><br>I've attached an example that uses the particle tracking to create timelines that track the flow past a hemisphere. It is the same as this case: <a href="http://www.mcs.anl.gov/%7Efischer/cfd/cfd.html" target="_blank">http://www.mcs.anl.gov/~fischer/cfd/cfd.html</a>. Also, there is a video that shows the particles (from the exact setup that I'm sending you) here: <a href="http://www.mcs.anl.gov/%7Efischer/mov.mp4" target="_blank">http://www.mcs.anl.gov/~fischer/mov.mp4</a>.<br>
<br>The particle routines are all called from userchk. They are:<br>particle_init - initiates particles, can be as complex or simple as you need<br>particle_advect_std - advects particles by interpolating velocity values at the current location and using history velocity values for AB3<br>
particle_out - outputs particle data...sometimes using poorly coded MPI ;)<br><br>The main arrays are:<br>pts - keeps particle data<br>vel - keeps velocity history for AB3 and for output if you're interested<br>npart - the local number of particles<br>
partpt - array of global particle numbers, for tracking<br><br>The only parameter that you need to adjust in SIZE is lpart for the maximum number of particles. If it's too small, Nek should tell you.<br><br>Justin<br>
<br><div class="gmail_quote">On Wed, Jun 29, 2011 at 2:42 PM, <span dir="ltr"><<a href="mailto:nek5000-users@lists.mcs.anl.gov" target="_blank">nek5000-users@lists.mcs.anl.gov</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hi Alireza,<br>
<br>
Let me check what is a current status of development for a complete set of Lagrangian particle tracking routines.<br>
<br>
My understanding that the subroutine particle_advect is written for the old interpolation w/ parameter mr -- we need to update it. This subroutine has to be used in the timestep loop called from usrchk after one interpolates (w/ intpts) velocity field (to vvel) at coordinates of the most recent particle location rtl -- hmm, I do not see how this array vvel with interpolated velocity data is then passed to the subroutine particle_advect...<br>
<br>
Let me look further and get back to you later.<br>
Aleks<div><div></div><div><br>
<br>
<br>
<br>
On Wed, 29 Jun 2011, <a href="mailto:nek5000-users@lists.mcs.anl.gov" target="_blank">nek5000-users@lists.mcs.anl.<u></u>gov</a> wrote:<br>
<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Hi,<br>
<br>
I have couple of questions regarding the subroutine given for Lagrangian particle tracking at the following wiki page and I wonder if there are any hints.<br>
<br>
<a href="http://nek5000.mcs.anl.gov/index.php/Data_processing_example" target="_blank">http://nek5000.mcs.anl.gov/<u></u>index.php/Data_processing_<u></u>example</a><br>
<br>
- Where should this subroutine be inserted?<br>
- What are the variables "rtl" and "mr" representing?<br>
- How to set the initial positions of the particles?<br>
- Should the constant parameters "npart" and "dt_p" be inserted in SIZE file?<br>
<br>
<br>
Thanks in advance,<br>
<br>
<br>
Regards,<br>
Alireza Karimi<br>
<br>
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