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March 13, 2011, 17:34 |
How to change density in OpenFoam
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#1 |
New Member
Wei Zhao
Join Date: Mar 2010
Posts: 28
Rep Power: 16 |
Hi, all
I have done some simulation of aircraft propeller using MRFSimpleFoam, and the result goes well with ANSYS CFX. MRFSimpleFoam is used for incompressible steady state simulation. Now I want to change the flow density to see the performance of the propeller. It is very easy to change it in CFX, but how can I change the density of flow in OpenFoam? I have read some theads said that OpenFoam use kinematic viscosity which is normalized by the density, and pressure is too. I have changed the reference pressure in fvSolution and mu in transportProperties, but the axial thrust does not change . Could anyone tell me how can I change the density? Thanks in advance. |
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March 14, 2011, 05:00 |
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#2 |
Senior Member
Alberto Passalacqua
Join Date: Mar 2009
Location: Ames, Iowa, United States
Posts: 1,912
Rep Power: 36 |
You have to change the viscosity:
nu = mu/rho being mu -> dynamic viscosity nu -> kinematic viscosity rho -> density 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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March 14, 2011, 05:51 |
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#3 |
New Member
Wei Zhao
Join Date: Mar 2010
Posts: 28
Rep Power: 16 |
Hi, Alberto
Thanks very much for your reply. I have changed the viscosity, but the axial force still not change. I use k-epsilon model, so should I change k and e? thanks |
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March 14, 2011, 06:00 |
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#4 |
New Member
Wei Zhao
Join Date: Mar 2010
Posts: 28
Rep Power: 16 |
Oh, I forgot to post my transportProperties file.
the original one is as follows: /*--------------------------------*- C++ -*----------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: 1.5 | | \\ / A nd | Web: http://www.OpenFOAM.org | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ FoamFile { version 2.0; format ascii; class dictionary; object transportProperties; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // transportModel Newtonian; nu nu [0 2 -1 0 0 0 0] 1e-05; CrossPowerLawCoeffs { nu0 nu0 [0 2 -1 0 0 0 0] 1e-06; nuInf nuInf [0 2 -1 0 0 0 0] 1e-06; m m [0 0 1 0 0 0 0] 1; n n [0 0 0 0 0 0 0] 1; } BirdCarreauCoeffs { nu0 nu0 [0 2 -1 0 0 0 0] 1e-06; nuInf nuInf [0 2 -1 0 0 0 0] 1e-06; k k [0 0 1 0 0 0 0] 0; n n [0 0 0 0 0 0 0] 1; } |
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March 14, 2011, 06:09 |
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#5 |
New Member
Wei Zhao
Join Date: Mar 2010
Posts: 28
Rep Power: 16 |
Oh, sincerely sorry everyone. I use the libturboPerformance.so to calculate the performance of rotor. I forgot to change the density there.
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November 18, 2012, 18:56 |
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#6 | |
Senior Member
Join Date: Nov 2012
Posts: 171
Rep Power: 14 |
Quote:
Now in my simulations, there are two streams: one is air and the other is pure methane. So in this case, how to set the nu? Is it still correct to give an approximate uniform value for the whole field? Thank you very much. |
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February 25, 2013, 05:48 |
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#7 | |
New Member
harikrishnan
Join Date: Sep 2012
Posts: 7
Rep Power: 14 |
Quote:
Hi I am new to openFoam. Did you get the answer for your question.?? please tell me how can we tackle this issue.. |
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December 11, 2014, 09:36 |
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#8 |
New Member
otadol
Join Date: Nov 2014
Posts: 14
Rep Power: 12 |
Hello hayhari,
I have just a simple question : Is it possible to set a "density" into a block to let more or less the fluid going throught? I mean, they is only the permeability to set it or there is other Options? Thanks for your reply |
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November 5, 2018, 11:37 |
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#9 | |
New Member
Xiaolu Wang
Join Date: Apr 2018
Location: Southampton, UK
Posts: 5
Rep Power: 8 |
Quote:
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