Adaptive CFL parameters

shahidhk21 · January 22, 2022, 10:14

I need to some help in deciding adaptive CFL parameters for my case
It is a 3-d, supersonic, viscous, steady, turbulent flow case with flow in x direction, RANS simulation. I have given value of CFL=0.5, Euler Implicit scheme, FGMRES linear solver with ILU preconditioner.

My solution initially converges for some iterations then starts to diverge.

I have given parameter CFL_ADAPT=(0 , 1.2, 0.5, 100 ) respectively based on given template and tutorial cases. I am not sure about these parameters.

Can anyone give me some more idea about adaptive CFL and how I can modify these parameters for convergence of my results?

Also, can we print CFL value for each iteration in our console as screen output just like residual?

I am new to SU2 and CFD.

PENGGEGE777 · January 23, 2022, 06:05

Hi, you can find more info about CFL adaptive in su2 homepage or config_template.

Usually, I set parameter = (0.1, 1.1, 1, 100)-----------CFL factor up, down, min, max.

Also, from your descripttion, maybe divergence of your simulation is not due to CFL number. You can check your mesh, bounadry contidions, numerical schemes, etc.

shahidkhan · January 23, 2022, 07:36

Sure, I will try with that. I also think that there is some issue with my grid but i wanted to try other things first before going to the grid part. I will try with this. If not I will look into other things

January 22, 2022, 10:14	Adaptive CFL parameters	#1
shahidhk21 New Member Shahid Khan Join Date: Jan 2022 Posts: 8 Rep Power: 4	I need to some help in deciding adaptive CFL parameters for my case It is a 3-d, supersonic, viscous, steady, turbulent flow case with flow in x direction, RANS simulation. I have given value of CFL=0.5, Euler Implicit scheme, FGMRES linear solver with ILU preconditioner. My solution initially converges for some iterations then starts to diverge. I have given parameter CFL_ADAPT=(0 , 1.2, 0.5, 100 ) respectively based on given template and tutorial cases. I am not sure about these parameters. Can anyone give me some more idea about adaptive CFL and how I can modify these parameters for convergence of my results? Also, can we print CFL value for each iteration in our console as screen output just like residual? I am new to SU2 and CFD.

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January 23, 2022, 06:05		#2
PENGGEGE777 Member PENG YAN Join Date: Jul 2021 Location: Italy Posts: 34 Rep Power: 4	Hi, you can find more info about CFL adaptive in su2 homepage or config_template. Usually, I set parameter = (0.1, 1.1, 1, 100)-----------CFL factor up, down, min, max. Also, from your descripttion, maybe divergence of your simulation is not due to CFL number. You can check your mesh, bounadry contidions, numerical schemes, etc.

January 23, 2022, 07:36		#3
shahidkhan Member Shahid Khan Join Date: Jan 2020 Posts: 35 Rep Power: 6	Sure, I will try with that. I also think that there is some issue with my grid but i wanted to try other things first before going to the grid part. I will try with this. If not I will look into other things