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Discrete vs Continuous Adjoint solution variable: Scaling/normalization issue?

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Old   December 25, 2016, 15:57
Default Discrete vs Continuous Adjoint solution variable: Scaling/normalization issue?
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Asitav Mishra
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Hello all,

Why are the Discrete adjoint solution (psiRho, for ex) values order of magnitude different from the Continuous adjoint solution values? Referring to the QuickStart tutorial, I could match exactly with the continuous adjoint solution. However, when run with MATH_PROBLEM=DISCRETE_ADJOINT option with the same config file (inv_NACA0012.cfg) the adjoint solution variables is order of magnitude different than the continuous adjoint. See attached figures. The figures also include Continuous vs Discrete surface sensitivity plot.

I actually verified the Discrete adjoint sensitivity with the Direct Derivatives, besides verifying dCd/dM from FD with Disc Adj. Is there some internal normalization for Disc Adjoint solution that is saved in adjoint restart file?
Any pointers would help.
Attached Images
File Type: png discVsDirDiff.png (8.2 KB, 51 views)
File Type: png surfSensCmp.png (8.9 KB, 51 views)
File Type: png adjCont.png (13.2 KB, 50 views)
File Type: png adjDisc.png (38.2 KB, 49 views)
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Old   March 19, 2018, 10:12
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Zen
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Zeno
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This is something I am also experiencing. Did you find the reason for this in the end?

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Old   November 21, 2018, 20:11
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Robert_87
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I guess you used two different configuration files for continuous and discrete runs.

You might look at the REF_DIMENSIONALIZATION in the configuration file and make sure that the non-dimensionalization is the same between the two adjoint runs.
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