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Divergency problem by computing a steady base flow with SFD

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Old   May 30, 2018, 12:07
Default Divergency problem by computing a steady base flow with SFD
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Siqi Yin
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Hello, I am running a SFD-solver which is based on icoFoam. The SFD-solver (SFD: Selective Frequency Damping ) computes a steady laminar flow over a plate where a cylinder roughness is set on.



The grid is very fine so I computed with very small time step (1.5e-5 s) so that the CFL-number would be never above 0.9 . For the system/fvSolution file I set up the pressure (for solving the pressure Poisson equation) as
p
{
solver PCG;
preconditioner DIC;
tolerance 5e-09;
relTol 0.005;
}


at the beginning, then I thought the tolerance could be chosen with a higher one, so I changed it to 1e-8. After some while, the CFL-number began to drop and then somehow increased over 1.0, the case exploded .


Could someone tell me why the CFL-number first dropped and then increased? Can I save my case by changing the tolerance to 5e-9 again?
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Old   May 30, 2018, 12:15
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Siqi Yin
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The equation system is changed in the icoFoam to



fvVectorMatrix UEqn
(
fvm::ddt(U)
+ fvm::div(phi, U)
- fvm::laplacian(nu, U)
+ fvm::Sp(chi, U) // added
- fvc::Sp(chi, Ubar) // added
);

which is the SFD method . It can compute a steady base flow field U for the perturbation computation in the transition analysis.
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Old   January 30, 2024, 06:23
Default Help regarding SFD implementation
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Orissa
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I want to implement Selective Frequency Damping (SFD) to icoFoam solver to get the steady state solution can you please help regarding this how can i achive this.

Thanks !!
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Old   May 8, 2024, 10:06
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Ghazaleh Ahmadi
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Quote:
Originally Posted by pratyush_6174 View Post
I want to implement Selective Frequency Damping (SFD) to icoFoam solver to get the steady state solution can you please help regarding this how can i achive this.

Thanks !!
I also need to use it for combustion to get steady flames. Can you tell me how you managed to do so?
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