Divergence Problem SU2

Moharam · May 18, 2018, 19:20

Hello Everyone
I'm using SU2 v5 for a 2D Incomp. RANS case for a very simple airfoil but it never converges?

I tried to reduce the CFL no , Multigrid = 0 , Used JST and ROE
Increased the Max number of iterations of the linear solver for the implicit formulation to a 100
Never converge, the residuals in the beginning increase and the Cd increase, then at some point the residuals fluctuate around a certain value and the Cd keeps decreasing

I'd appreciate any help

)
Thanks very much

jcownbey · December 30, 2019, 21:25

Moharam,

First, I would check to make sure you have an adequate mesh and the correct BC's and rerun the simulation. Usually a CFL= 1 is a good start for an airfoil. I'd also increase the number of iterations. The residuals only indicate when to start checking for convergence of the solution and do not indicate when convergence actually occurs. (e.g. the residual can converge, but your solution may not necessarily converge). You may need to visualize a variable between two different iteration numbers a few hundred iterations apart.

If you require more help, then you should post your config file and maybe a picture of your mesh.

May 18, 2018, 19:20	Divergence Problem SU2	#1
Moharam New Member Ahmed Join Date: Nov 2017 Posts: 15 Rep Power: 9	Hello Everyone I'm using SU2 v5 for a 2D Incomp. RANS case for a very simple airfoil but it never converges? I tried to reduce the CFL no , Multigrid = 0 , Used JST and ROE Increased the Max number of iterations of the linear solver for the implicit formulation to a 100 Never converge, the residuals in the beginning increase and the Cd increase, then at some point the residuals fluctuate around a certain value and the Cd keeps decreasing I'd appreciate any help ) Thanks very much

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December 30, 2019, 21:25		#2
jcownbey Member Join Date: Dec 2019 Posts: 30 Rep Power: 6	Moharam, First, I would check to make sure you have an adequate mesh and the correct BC's and rerun the simulation. Usually a CFL= 1 is a good start for an airfoil. I'd also increase the number of iterations. The residuals only indicate when to start checking for convergence of the solution and do not indicate when convergence actually occurs. (e.g. the residual can converge, but your solution may not necessarily converge). You may need to visualize a variable between two different iteration numbers a few hundred iterations apart. If you require more help, then you should post your config file and maybe a picture of your mesh.