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Grid Motion in Parallel

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Old   April 21, 2020, 19:56
Default Grid Motion in Parallel
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Hi, I'm having a small issue with my dynamic mesh UDF. I am running in parallel and end up doing some calculations to figure out how much to displace each wall vertex on my mesh. It seems to work fine except when I hit update dynamic mesh and run 1 iteration, it performs the grid motion twice. I also display a message for how much volume total I am displacing. When I hit update dynamic mesh, the message displays twice. The first tie it shows the correct volume to move the mesh. The second message shows exactly double the first volume. As shown, I use a += statement to loop through all the cells to get this value. This tells me that the entire thing is running twice for some reason. I'm running on 28 processors. The calculations across the processors works great, but again, it's like the function runs twice when I hit update dynamic mesh. Any ideas why this might happen? Could this be something to do with how node 0 communicates with the host? Maybe it's running my entire UDF twice?
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Old   April 22, 2020, 04:42
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To debug it, print myid within Message. This will tell you whether the message is being printed by host or node, and which node, of course. And that might be helpful in determining why the code runs twice.

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Old   April 22, 2020, 05:15
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AlexanderZ will become famous soon enoughAlexanderZ will become famous soon enough
it is recommended to use
for global summation

#if PARALLEL means nodes + host

however, you have (I_AM_NODE_ZERO_P) so your message function should be executed just once

Usually, Message0 is used to write output to console in case of parallel consideration

If it doesn't help, show the whole code, may be problem is somewhere else
best regards

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dpm, grid motion

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