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convergence problem in 2D steady supersonic flow |
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November 4, 2014, 08:10 |
convergence problem in 2D steady supersonic flow
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#1 |
New Member
mohamed mohsen
Join Date: Oct 2012
Posts: 29
Rep Power: 14 |
Hello Guys ..
I'm simulating a flow over a 2D supersonic airfoil with fluent, steady state, density based solver, structured quad cells with yplus around 2 and SA turbulence model, boundaries are velocity inlet and pressure outlet the problem is the solution doesn't converge such that the residuals are fixed at certain values and the mass flow rate and pressures at certain locations keep oscillating periodically with large amplitude. i tried to reduce the CFL up to 0.01! oscillations exist with less amplitude. Can anybody help with this problem im stuck! |
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November 5, 2014, 07:47 |
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#2 |
New Member
AAA
Join Date: Nov 2014
Posts: 7
Rep Power: 12 |
Hello
As you know, there are various reasons why the solution doesn't converge. I guess the domain of your solution is too small. How big is the size of domain? At least the domain behind airfoil must be approximately 10~15 times the chord length. |
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November 5, 2014, 08:47 |
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#3 |
New Member
mohamed mohsen
Join Date: Oct 2012
Posts: 29
Rep Power: 14 |
yeah the domain behind the airfoil is about 10 times the chord .. i tried pressure inlet boundary and its much much more better than velocity inlet with little oscillations ,, i will try to reduce the CFL with the pressure boundary
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November 5, 2014, 19:58 |
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#4 | |
New Member
AAA
Join Date: Nov 2014
Posts: 7
Rep Power: 12 |
I found same problem with your problem.
Please look at this thread. http://www.cfd-online.com/Forums/fluent/112445-pressure-far-field-vs-velocity-inlet-pressure-outlet.html Quote:
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November 6, 2014, 08:06 |
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#5 |
New Member
mohamed mohsen
Join Date: Oct 2012
Posts: 29
Rep Power: 14 |
thank you bro ,, but it seems like pressure boundaries also have fluctuations , i will try to extend the domain much more ans see
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