Incomp. LES in pisoFOAM, how to set up Smagorinsky model with van Driest dampin
Hi all
Im new to OpenFOAM and I'm using v2.1.0 release. My question is regarding the Smagorinsky model implemented in this release. I used the motorBike tutorial to set up an incompressible LES simulation, and to use the Smagorinsky model I specify this in the LESProperties file. So far so good, I get the simulation to run as I anticipated. However, I'm not sure if van Driest damping is incorporated in the standard implementation of the standard Smagorinsky model? From what I have managed to figure out from the file Smagorinsky.H which is located in : $OpenFOAM_Installation_dir/OpenFOAM-2.1.x/src/turbulenceModels/incompressible/LES/Smagorinsky it seems to me van Driest damping is not included. My question is, how do I specify that I would like to use the van Driest damping? Right now, for the boundary conditions for nuSgs I have the Spalding wall function specified on my no-slip boundaries. Cheers |
Set
delta vanDriest; into LESProperties. |
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/Jan |
Hmm, I get an error when I try to activate the van Driest damping. The only thing I change is to set
Code:
delta vanDriest; Code:
delta vanDriest; Code:
/*---------------------------------------------------------------------------*\ Code:
#0 Foam::error::printStack(Foam::Ostream&) in "/home/ojan/OpenFOAM/OpenFOAM-2.1.x/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" |
hi!
i'm not that familiar with les, specially in of, yet, but have you check out the tutorials: /tutorials/compressible/rhoPimpleFoam/les/pitzDaily/constant/LESProperties /tutorials/combustion/fireFoam/les/smallPoolFire3D/constant/LESProperties /tutorials/combustion/fireFoam/les/oppositeBurningPanels/constant/LESProperties /tutorials/combustion/fireFoam/les/smallPoolFire2D/constant/LESProperties /tutorials/combustion/XiFoam/les/pitzDaily3D/constant/LESProperties /tutorials/combustion/XiFoam/les/pitzDaily/constant/LESProperties /tutorials/incompressible/channelFoam/channel395/constant/LESProperties also you're running a transient solver.. try checking your settings with a steady-state one.. then switch over. i normally find it harder to get a transient solver to work at first hope it helps! regards |
Thanks for the reply, I will go through the tutorials. However, the above error was created by activating the van Driest damping. Before that, the simulation was running as it should...
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then i guess the problem is the annoying one.. solver/schemes/timestep settings..
can't help you much there.. too many parameters at this point sry :( |
It is actually a bug, since it happens even in tutorials, if you use vanDriest. I reported it: http://www.openfoam.org/mantisbt/view.php?id=445
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Short update: I investigated more using the pisoFoam/pitzDaily tutorial. The problem originates from the exp at line 93:
(kappa_/Cdelta_)*((scalar(1) + SMALL) - exp(-y/ystar/Aplus_))*y I inspected the values of the argument at the first iteration and I obtained: min(y) -1e+15 max(y) 0.000566292 min(ystar) 8.46024e-06 max(ystar) 1 It seems the minimum wall distance is computed incorrectly and leads to an overflow of the exponential function. |
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one last thought.. you said the error appears even in the tutorials right? but does the error occurs with the "stock settings"? cuz.. i mean.. say you have a tutorial and change the turbulence settings as you need.. have you checked the possibility of a mesh error?? check that for your mesh and the tutorial one... YplusLES should help you with the checking... if mesh is not the issue, my hands are now tight.. sry and good luck! :o |
Some work with git bisect showed that the problem is related to commit c06792759a720eb9d1494b4b4b0c3a86d21c20b0
http://www.openfoam.org/mantisbt/view.php?id=448 |
Ok great work, thanks alberto. I tried the OpenFoam v2.0 release and that was ok.
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OpenCFD fixed the bug in git for 2.1.x (See bug-report).
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Great. I updated the release and now it works using van Driest (at least it doesn't crash). /Jan |
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I wonder if there is a way to fix the bug in OpenFoam 2.0.1. For some reason, I kind of have to use this version of OpenFoam. Could you please give me some hits? My OS system is Ubuntu 11.04. Best regards Peter |
van Driest damping fuction
Hi all,
Any body can point me to a paper for the van Driest damping function implemented in the Openfoam. Thanks. |
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http://www.cfd-online.com/Wiki/Near-...for_LES_models http://www.fluidosol.se/thesismod/paper5.pdf Hope it works for you. |
The van Driest damping function in OpenFoam is applied in different way. In OpenFoam, the damping is derived by changing the filter width, depending on the distance from the wall. You may want to look at equation 2.7 in this document
http://www.tfd.chalmers.se/~hani/kur...jectReport.pdf Any reference for that? Quote:
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Hi ehk,
in my opinion the statement for Delta in the report you posted is wrong. When I check eq. 2.7 with https://github.com/OpenFOAM/OpenFOAM...nDriestDelta.C I can see a difference. It should be: Delta = min[Delta , kappa/C_d * (1 - exp(yPlus/APlus))*y] and not Delta = min[Delta , kappa/C_d] * (1 - exp(yPlus/APlus))*y So the damping function only effects the right term of the min expression. Can someone confirm this? |
Hello, I am doing LES turbulence simulation using OpenFOAM3.0.1, and have some questions about the turbulenceProperties in the constant folder of pitzDaily in tutorials, I don't understand what LESdelta means, is it related to filter width?
Code:
simulationType LES; PHP Code:
Thank you in advance! Best regards, Esther |
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