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Old   August 23, 2017, 12:55
Question Adjoint Calculation Error
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tom pratt
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Hi,
I am running a 2D aerofoil optimization using V5.0.0;
the flow solution is converged but each log_adjoint.out file shows the following:
Code:
log10[Maximum residual]: -inf.
Maximum residual point 0, located at (0, 0).

 Iter    Time(s)   Res[Psi_Rho]     Res[Psi_E]      Sens_Geo      Sens_AoA
    0   0.524635     -32.000000     -32.000000    0.0000e+00    0.0000e+00
CSysSolve::FGMRES(): system solved by initial guess.
when in fact the flow solution file shows the following:
Code:
----------------------- Residual Evolution Summary ----------------------
log10[Maximum residual]: -2.83626.
Maximum residual point 11866, located at (0.191485, -0.0191805).
----------------------------------------------------------------------
just before writing and exiting.
the adjoint gradients are then calculated to be zero (i think as a result of the above issue)
any help would be highly appreciated!
if more information on the .cfg file or .su2 grid is needed let me know.
Many thanks!
Tom
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Old   August 24, 2017, 18:45
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Alejandro Quirós
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What are the values you are using in the reduction factors of the CFL? This issue can happen if they are 0 since you'll be using a CFL of 0.
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Old   August 29, 2017, 13:22
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tom pratt
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Hi,
the CFL was positive with a value of around 0.5-1.5.
the reduction factors were around 1.0-0.9.
I have now gotten around the problem by modifying a cfg file from the NACA0012 steady optimization Testcase for use with my own grid and conditions.
However, i am now facing the problem of the design returning to its original condition after a single 'good' design iteration. This issue is being discussed in another Thread.
Thanks for the assistance.
Tom
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