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Divergency problem by computing a steady base flow with SFD |
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May 30, 2018, 12:07 |
Divergency problem by computing a steady base flow with SFD
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#1 |
New Member
Siqi Yin
Join Date: May 2018
Location: Stuttgart, Germany
Posts: 2
Rep Power: 0 |
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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May 30, 2018, 12:15 |
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#2 |
New Member
Siqi Yin
Join Date: May 2018
Location: Stuttgart, Germany
Posts: 2
Rep Power: 0 |
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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January 30, 2024, 06:23 |
Help regarding SFD implementation
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#3 |
New Member
Orissa
Join Date: Feb 2022
Posts: 15
Rep Power: 4 |
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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May 8, 2024, 10:06 |
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#4 |
New Member
Ghazaleh Ahmadi
Join Date: Aug 2018
Posts: 1
Rep Power: 0 |
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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cfl number, icofoam, pressure tolerance |
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