How to visualize highly distorted mesh

lingdeer · November 12, 2011, 18:50

I am running 2 way FSI simulations and my simulation crashed as I lower my young modulus from 1e7 to 1e5. (1e7 worked but 1e5 crashed). The error is failure in reading mesh displacement, because of highly distorted elements. I wonder how can I visualize and check the region where the mesh distorted/collapsed to see how I can improve the mesh to improve the results. I read the CFD post manual but it is unclear how I can visualize and fix the mesh.

Thanks a lot!

ghorrocks · November 13, 2011, 17:55

So is your question how do we view the mesh, or how do I see what is happening to find the problem area?

lingdeer · November 13, 2011, 18:18

Yes. I want to know where is the location of the problematic area and what is causing the problem. Thanks!

ghorrocks · November 13, 2011, 19:19

If the run crashed before it wrote an output file then re-run it with a finer time step and saving an output file every time step. Hopefully that can capture the mesh motion enough that you can pick what went wonky.

lingdeer · November 13, 2011, 19:23

Thanks ghorrocks. The funny thing is when I reduce the time step the simulation tends to crash and stop at earlier time step than using a coarser time step.
Also, in some cases the simulation just crashed at the first time step before writing any output file.

ghorrocks · November 13, 2011, 19:28

Then your model is highly unstable. I would use a E which is more likely to work (maybe 1e6?) and that might give you a clue as to where the problem is.

lingdeer · November 13, 2011, 19:31

Cool~ Thank you very much! I will try it out.

November 12, 2011, 18:50	How to visualize highly distorted mesh	#1
lingdeer Member Lingdeer Join Date: Jul 2011 Posts: 49 Rep Power: 15	I am running 2 way FSI simulations and my simulation crashed as I lower my young modulus from 1e7 to 1e5. (1e7 worked but 1e5 crashed). The error is failure in reading mesh displacement, because of highly distorted elements. I wonder how can I visualize and check the region where the mesh distorted/collapsed to see how I can improve the mesh to improve the results. I read the CFD post manual but it is unclear how I can visualize and fix the mesh. Thanks a lot!

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November 13, 2011, 17:55		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,870 Rep Power: 144	So is your question how do we view the mesh, or how do I see what is happening to find the problem area?

November 13, 2011, 18:18		#3
lingdeer Member Lingdeer Join Date: Jul 2011 Posts: 49 Rep Power: 15	Yes. I want to know where is the location of the problematic area and what is causing the problem. Thanks!

November 13, 2011, 19:19		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,870 Rep Power: 144	If the run crashed before it wrote an output file then re-run it with a finer time step and saving an output file every time step. Hopefully that can capture the mesh motion enough that you can pick what went wonky.

November 13, 2011, 19:23		#5
lingdeer Member Lingdeer Join Date: Jul 2011 Posts: 49 Rep Power: 15	Thanks ghorrocks. The funny thing is when I reduce the time step the simulation tends to crash and stop at earlier time step than using a coarser time step. Also, in some cases the simulation just crashed at the first time step before writing any output file.

November 13, 2011, 19:28		#6
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,870 Rep Power: 144	Then your model is highly unstable. I would use a E which is more likely to work (maybe 1e6?) and that might give you a clue as to where the problem is.

November 13, 2011, 19:31		#7
lingdeer Member Lingdeer Join Date: Jul 2011 Posts: 49 Rep Power: 15	Cool~ Thank you very much! I will try it out.