Simulation courant number shoots up even with very low delta t

[Platinumd1991]

I have been using NekRS very successfully for multiple high Re flows. However, recently I have tried to run Re = 2240 for a new project and the courant number keeps shooting up regardless if I lowered delta t or refined the mesh. I ran the same case with Nek5000 and no issues like this occur. Is this a bug with NekRS?

**step= 52598 t= 1.82207840e+02 dt=8.0e-05 C= 4.27 UVW: 2 P: 22 eTime=

2.11e-01, 2.71779e+03 s
step= 52599 t= 1.82207920e+02 dt=8.0e-05 C= 5.82 UVW: 3 P: 23 eTime=
2.09e-01, 2.71800e+03 s
step= 52600 t= 1.82208000e+02 dt=8.0e-05 C= 8.76 UVW: 3 P: 25 eTime=
2.30e-01, 2.71823e+03 s
copying solution to nek
calling nek_userchk ...
52600 1.82208000000E+02 7.26226313888E+00 7.26559569350E+00
-3.33255462393E-03 1dragx
52600 1.82208000000E+02 -2.88376652997E-03 -2.62383438671E-03
-2.59932143255E-04 1dragy
52600 1.82208000000E+02 -2.16552739071E-04 1.40683273030E-16
-2.16552739071E-04 1dragz
52600 1.82208000000E+02 7.26226313888E+00 7.26559569350E+00
-3.33255462393E-03 2dragx
52600 1.82208000000E+02 -2.88376652997E-03 -2.62383438671E-03
-2.59932143255E-04 2dragy
52600 1.82208000000E+02 -2.16552739071E-04 1.40683273030E-16
-2.16552739071E-04 2dragz
dump history points
step= 52601 t= 1.82208080e+02 dt=8.0e-05 C= 15.38 UVW: 3 P: 30 eTime=
3.06e-01, 2.71854e+03 s
step= 52602 t= 1.82208160e+02 dt=8.0e-05 C= 45.05 UVW: 3 P: 37 eTime=
3.26e-01, 2.71886e+03 s
Unreasonable CFL! Dying ...
**

[stgeke]

Could you please provide more details about your case.

[Platinumd1991]

Hi, Apologies for the late reply. I am running a 3D flat plate at Re = 2240 in a confined setting( no-slip around walls). Please find a sample of my case. compile_nekRS.slurm <https://drive.google.com/file/d/1l698rqMkIwYoLob0e8sJJkMSeJfoiFAH/view?usp=drive_web> fpre2240_B00_M1_3D.oudf <https://drive.google.com/file/d/1GzRd0cZWiDV8_OLJ5_ZlyoEfcYbbwIE0/view?usp=drive_web> fpre2240_B00_M1_3D.par <https://drive.google.com/file/d/1P2fZNdEITFZmCivSHQazbd_V0HFNI9jj/view?usp=drive_web> fpre2240_B00_M1_3D.re2 <https://drive.google.com/file/d/1JcKIFqDXp5e07owGiR82iLsru0j78wsj/view?usp=drive_web> fpre2240_B00_M1_3D.slurm <https://drive.google.com/file/d/1bAezztXwy6WN0T0HxBi93IQviOSMyCk9/view?usp=drive_web> fpre2240_B00_M1_3D.udf <https://drive.google.com/file/d/1oayhZ-Dq9bsYdhLY_sel7DEsK9NnpYGM/view?usp=drive_web> fpre2240_B00_M1_3D.usr <https://drive.google.com/file/d/1iCu9k2RYlO_MErDaTzmpKHoMLJO51JPF/view?usp=drive_web>

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On Tue, Feb 14, 2023 at 6:42 PM stgeke ***@***.***> wrote: Could you please provide more details about your case. — Reply to this email directly, view it on GitHub <#480 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AL3HBISUR33VRSD7FP236E3WXMZPRANCNFSM6AAAAAAU26XMYM> . You are receiving this because you authored the thread.Message ID: ***@***.***>