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#1 |
Senior Member
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Hi Foamers,
has anyone some experience in using the pimpleFoam solver? I'm trying to apply it on a low Mach, high Re airfoil in a jet flow. The airfoil has a separation bubble just after the leading edge as it has a big camber, so simpleFoam is not able to obtain a stable bubble. I tried with pimpleFoam and a big CFL = 5, using standard setups for fvSchemes and fvSolution (like in the tutorial), but I can't obtain anything meaningful. So, before starting to play with schemes and solver, is this solver suitable for this external aerodynamics problems? Thanks a lot! Ivan |
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#2 |
Senior Member
ata kamyabi
Join Date: Aug 2009
Location: Kerman
Posts: 323
Rep Power: 18 ![]() |
Hi Ivan
As you know pimpleFoam is for: Large time-step transient solver for incompressible, flow using the PIMPLE (merged PISO-SIMPLE) algorithm.Turbulence modelling is generic, i.e. laminar, RAS or LES may be selected. So I think you select right solver and problem is from other point. Best regards Ata |
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#3 | |
Senior Member
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Quote:
Ivan |
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#4 | |
Senior Member
Alberto Passalacqua
Join Date: Mar 2009
Location: Ames, Iowa, United States
Posts: 1,912
Rep Power: 36 ![]() ![]() |
Hi Ivan,
can you post a contour or some info about what you obtain with the pimpleFoam in your case? What are average Ma and Re? pimpleFoam is basically pisoFoam with substep iterations in order to achieve convergence with larger time steps/Courant numbers, allowing variable under-relaxation. In other words, if pisoFoam (unsteady incompressible solver) is suitable for your case, pimpleFoam is as well. Quote:
![]() Best,
__________________
Alberto Passalacqua GeekoCFD - A free distribution based on openSUSE 64 bit with CFD tools, including OpenFOAM. Available as in both physical and virtual formats (current status: http://albertopassalacqua.com/?p=1541) OpenQBMM - An open-source implementation of quadrature-based moment methods. To obtain more accurate answers, please specify the version of OpenFOAM you are using. ![]() |
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#5 |
Senior Member
ata kamyabi
Join Date: Aug 2009
Location: Kerman
Posts: 323
Rep Power: 18 ![]() |
Hi Ivan
You told (like in the tutorial). Absolutely when I sow that you are a senior member I write "As you know". However The problem was thatyou do not explain enough. In example how residuals behave? Is it converges? How much is CFL? What kind of B.C.s you use? Do you use nNonarthogonalCorrection? What number? And alberto you are a very smart. I think Ivan gives you a response as sent for me. Best regards Ata |
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#6 | |
Senior Member
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Quote:
I'm sorry not to post any contour of my test case, on wednesday when I'm back at the office I will do it. My test case parameters are: 2D asymmetric airfoil Mach about 0.1, Re about 5x10^5, AOA = 0° (so the stagnation point is on the suction side, there is a separation on the pressure side identified by both experiments and other softwares calculations). I choose a SST k-omega RANS model, with low Re treatment of the walls (I've implemented the Menter's B.C. for omega, valid for y+ less than 3, k fixedValue 1e-10, my y+ is less than 2 everywhere). With pisoFoam I obtained a good result with Max CFL about 2 (gamma schemes and backward scheme for time), converged everywhere excepting for the separation bubble, where I have a small release of unsteady structures (so the bubble is not stable). Other partners involved in the same calculations, told me that they obtained a stable bubble using a large CFL value, and I repeated the same calculation with StarCCM+ with a very large CFL (more than 20) and I obtained I stable bubble (but with very bad CP on the airfoil, so OF did it better ![]() I decided to try with pimpleFoam in order to use a very high CFL as well, but for CFL higerh than 5 everything blows up, and even for CFL of the order of 5 the results are completely crazy. This is the story so far, on wednesday the images! @ATA I have to apologize with you if my answer sounded like a firing on you, I just want to say that my question was not on a theoretical point of view, but on a pratical one... |
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#7 |
Senior Member
ata kamyabi
Join Date: Aug 2009
Location: Kerman
Posts: 323
Rep Power: 18 ![]() |
Hi ivan
It's OK. Is your mesh is same in both runs (OF and StarCCM+)? I think may be your mesh is not a good one near separation point. May you send images of your mesh and velocity and pressure contours? And how much is order of residuals? Are they change or decrease or increase or oscillate? Best Regards Ata |
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#8 | |
Senior Member
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Quote:
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#9 |
Member
Aldo Iannetti
Join Date: Feb 2010
Posts: 48
Rep Power: 16 ![]() |
Hi,
Can you please have a look and test my PimpleSoam for turbulent and dynamic meshes for OF 1.5? Thanks Aldo |
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#10 |
Member
Manjura Maula Md. Nayamatullah
Join Date: May 2013
Location: San Antonio, Texas, USA
Posts: 42
Rep Power: 13 ![]() |
Hello Guys,
I was running a default case channel395 in OpenFOAM using pimpleFoam solver and it runs perfectly. But i put curved bottom wall using blockMeshDict. Than i run the simulation and it shows error- Foam::error: ![]() I don't understand why it doesn't work when i modifed the bottom wall as curved form. Help will be appreciated Manjura |
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