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August 9, 2013, 15:42 |
Cl and Cd values very high
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#1 |
New Member
Philip Brown
Join Date: Jun 2013
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Hi there.
I have managed to run my aerofoil simulation but I am getting very high values of Cd and Cl. I anticipated that there may be a bit of a problem with no modelling as a compressible flow (I used the SimpleFoam solver) but not to this extent! I have attached the my project folder if anyone can help. Thanks |
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August 10, 2013, 14:53 |
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#2 |
Senior Member
Ehsan
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August 10, 2013, 15:04 |
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#3 |
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Philip Brown
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Thanks immortality. Which filed would you need? I would guess posy processing, controldic and the whole of the 0 folder?
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August 10, 2013, 15:09 |
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#4 |
Senior Member
Ehsan
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Hi
0 folder constant and system if you want me run it otherwise whatever you know may the problem be there.
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August 10, 2013, 16:03 |
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#5 |
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Ehsan
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why you have set rhoInf 1000? is the environment water?
but you have: transportModel Newtonian; rho rho [ 1 -3 0 0 0 0 0 ] 0.42; nu nu [ 0 2 -1 0 0 0 0 ] 1.47e-05;
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Injustice Anywhere is a Threat for Justice Everywhere.Martin Luther King. To Be or Not To Be,Thats the Question! The Only Stupid Question Is the One that Goes Unasked. |
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August 10, 2013, 16:06 |
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#6 |
New Member
Philip Brown
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The environment is air at approx 11km. I have been trying to build this up from tutorials without knowing everything behind it and must have missed that. Would my rhoInf be 0.42 too or is there an equation that determines another value for it?
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August 10, 2013, 16:12 |
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#7 |
Senior Member
Ehsan
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yes it would be .42
correct it a look at other files carefully.run it and I have a look if another problem occurred.
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Injustice Anywhere is a Threat for Justice Everywhere.Martin Luther King. To Be or Not To Be,Thats the Question! The Only Stupid Question Is the One that Goes Unasked. |
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August 10, 2013, 16:16 |
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#8 |
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Philip Brown
Join Date: Jun 2013
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>.< silly me.. of course all the values ...inf are freestream aren't they. No wonder my values were so high as only the area what a true representation. So it takes the forcecoeffs actually pulls out a lift,drag, moment values and then divides them by 1/2 rho v^2 s. I think I see where I was going wrong. Thank you very much.
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August 10, 2013, 16:17 |
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#9 |
New Member
Philip Brown
Join Date: Jun 2013
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Values are now in the 0.02 area for drag which seems a lot better!
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August 11, 2013, 02:41 |
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#10 |
Senior Member
Ehsan
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then it has been resolved?
I'm glad.what about Cl? Send me your new settings.I want to have a look into it.
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Injustice Anywhere is a Threat for Justice Everywhere.Martin Luther King. To Be or Not To Be,Thats the Question! The Only Stupid Question Is the One that Goes Unasked. |
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June 30, 2015, 04:01 |
Very high Cl
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#11 |
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Somsankar Mondal
Join Date: Dec 2014
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P { margin-bottom: 0.08in; } Hi,
I was working on OpenFoam 2.3.1. Simulated some turbulence model with komega sst for flow past Circular Cylinder Re=100000, Cd=1.12, but always getting very high cl, rms =1. Please suggest, if there is any trick. |
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June 30, 2015, 05:38 |
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#12 |
Senior Member
Ehsan
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is your grid fine enough near the wall of the cylinder to include viscous layer?
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Injustice Anywhere is a Threat for Justice Everywhere.Martin Luther King. To Be or Not To Be,Thats the Question! The Only Stupid Question Is the One that Goes Unasked. |
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June 30, 2015, 06:02 |
Very high Cl
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#13 |
New Member
Somsankar Mondal
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I am using wallfunction, finess is such that, yplus value varying from 18 to 310, with average 172.
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June 30, 2015, 06:06 |
High Cl value
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#14 |
New Member
Somsankar Mondal
Join Date: Dec 2014
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please help, I have attached my case above.
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