# SU2 CD and CL Problems

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October 15, 2019, 14:52
SU2 CD and CL Problems
#1
New Member

Can
Join Date: Oct 2019
Posts: 4
Rep Power: 6
Hi everyone, i'm new to the SU2. SU2_CFD on calculation gives CD and CL(TOTAL) 10000 i don't know what i do. I share screenshoot and SU2 cfg files so help me to where am i wrong. Thank you.
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 October 15, 2019, 18:12 #2 Senior Member   Wally Maier Join Date: Apr 2019 Posts: 123 Rep Power: 7 Hiya! Thanks for using SU2. From a quick look at your screenshots, your simulation is diverging. The residuals printed indicate the energy is changing by 10^15 each iteration (not good haha). We like to see these numbera at -15. This is why the simulation is outputting the wrong coefficients. It looks like from your config, you are trying to run an Euler simulation. Some things you can try to help convergence are turn off multigrid (MULTIGRID=0) and reduce your CFL number. Often times issue arise due to mesh quality, that may be something to check in the future as well. Hope this helps! Let me know if you have any more questions! Wally

October 17, 2019, 07:13
#3
Member

Join Date: Mar 2017
Posts: 61
Rep Power: 9
Quote:
 Originally Posted by wallym Hiya! Thanks for using SU2. From a quick look at your screenshots, your simulation is diverging. The residuals printed indicate the energy is changing by 10^15 each iteration (not good haha). We like to see these numbera at -15. This is why the simulation is outputting the wrong coefficients. It looks like from your config, you are trying to run an Euler simulation. Some things you can try to help convergence are turn off multigrid (MULTIGRID=0) and reduce your CFL number. Often times issue arise due to mesh quality, that may be something to check in the future as well. Hope this helps! Let me know if you have any more questions! Wally

In addition, you should turn your simulation to 1st order by closing muscl option at least at the beginning of your run.