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 AAJ June 29, 2008 07:48

Convergence Problem

Hi all!!

I am running a coupled solver for an inviscid flow simulation, my geometry is very much complex.

I am using pressure far field and pressure outlet boundry conditions. Apart from residuals am monitoring Cl and Cd for the problem. Cl and Cd seems to be preety constant with max 0.5 percent variation from the max value.

The residuals of x,y,z velocity, continuity and energy are not converging. They come down to a max of 1e-2 and then they start going up again, or they fluctuate arround some mean value.

My question is that: Can i take this solution as a converged one? What are the factors that may exffect convergence of the problem?

 hailang June 29, 2008 23:00

Re: Convergence Problem

yes you are right,that is naumal , i think it can converge

you shoud wait enough long time.

 JaturongMokJok July 3, 2008 13:31

Re: Convergence Problem

I found the same problem , And I wait 23000 iterations , the solution doesn't converge , inlet pressure slightly decrease and decrease from -6000 Pa to -2900 Pa . I don't think it converge. I think some assumption is wrong. I use steady-state, inviscid, relaxation for pressure =0.2, for mom = 0.5 , other =1.0 , pressure-base, SIMPLE-scheme, all scheme pressure , mom, energy are second order upwind. the residual quite weird after 12000 iterations. Sry, my eng. is not good. how to fix it. I try MUSCL 3rd order, the residual has overshoot as manual explain. :(

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