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Old   March 11, 2013, 12:07
Default Adjoint simulation
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Samuele Z
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Dear All,

I have downloaded the last version of the solver from svn (here) and I have tried to solve the attached case (NACA0012).

I have tested 2 cases:
1. Mach = 0.15, with incompressible formulation
- the direct solution works very well
- the adjoint simulation fails
2. Mach = 0.8, compressible
- the direct solution works very well
- the adjoint simulation seems to work

Why this happen? Haven't you tested the adjoint solution for low Mach numbers?

Thanks a lot,
Samuele
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Old   March 12, 2013, 02:19
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Thomas D. Economon
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Hi Samuele,

Please check the post I left over in this thread on the topic: Turbulent flow at low Mach number.

Hope this helps!
T
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Old   March 20, 2013, 12:03
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Roberto Pieri
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Hi everybody,

I discovered that the problem with my mesh was related to elements near leading edge which didn't follow the curvature of the surface of the airfoil. Now results are very good.

I would also like to obtain adjoint solutions: both with drag and lift objective function.
In this case the ROE-2ND discretization gave me strange results (attached below); switching to JST, the solution seems to be better (both cases had been ran with drag obj function).
Problems arise when I want the adjoint solution with lift objective function; the solution is enormously slow (you can compare the residual.vs.iterations in both cases in the figures attached below).
Then I have some questions:
  • attached below you also find the config file, is there something wrong?
  • from my tests, it seems that the code reduces the CFL number when performing adjoint solution, is it right? Improving CFL could help me with adjoint-Lift convergence? If yes, which file should I modify?

http://dl.dropbox.com/u/27047350/Adjoint.zip

thank you in advance,
Roberto
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