Lift&Drag Coefficients is not accurate enough!

aut_iut · August 5, 2010, 09:41

Dear Foamers,

I'm working on a fixed/moving cylinder case. I used icoFoam solver for Re<300 and results are acceptable.
When Re exceed from 300 the drag coefficients become different from literature data. I'm using pisoFoam (with LES or RAS turbulence models) solver. For example for Re=500, experimental results say that avaraged drag coefficient should be 1.18, while OpenFoam calculates it in the range of 1.35-1.5 (depending on the changing parameters like BC and initial conditions).
I supposed maybe it is because of 3D effect. So I implemented the simulation for a 3D case. But still there is a considerable difference between my results and papers one.
I'm wondering if one could suggest me how to fix this problem.
Isn't it solver errors? To be honest I'm thinking about the accuracy of pisoFoam solver.
Regards,
Rasoul

niklas · August 5, 2010, 10:05

and grid dependency?

aut_iut · August 5, 2010, 10:13

Yes, of course!
My initial grid is fine and refining the mesh just increases the solution time without any considerable improve to results.
I also changed the divScheme in fvScheme file.

August 5, 2010, 09:41	Lift&Drag Coefficients is not accurate enough!	#1
aut_iut Member Rasoul Join Date: Feb 2010 Posts: 32 Rep Power: 16	Dear Foamers, I'm working on a fixed/moving cylinder case. I used icoFoam solver for Re<300 and results are acceptable. When Re exceed from 300 the drag coefficients become different from literature data. I'm using pisoFoam (with LES or RAS turbulence models) solver. For example for Re=500, experimental results say that avaraged drag coefficient should be 1.18, while OpenFoam calculates it in the range of 1.35-1.5 (depending on the changing parameters like BC and initial conditions). I supposed maybe it is because of 3D effect. So I implemented the simulation for a 3D case. But still there is a considerable difference between my results and papers one. I'm wondering if one could suggest me how to fix this problem. Isn't it solver errors? To be honest I'm thinking about the accuracy of pisoFoam solver. Regards, Rasoul

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Calculate aerodynamic coefficients with openfoam using only opensource programs	Xwang	OpenFOAM	20	May 20, 2016 11:26
implementation of diffusion coefficients and use of diffusion coefficients	stephan	OpenFOAM Running, Solving & CFD	0	February 28, 2010 14:30
Computing aerodynamic coefficients on bidimensional sections in 3D problems	Aragon	FLUENT	0	July 22, 2009 04:07
how to get more accurate accurate coefficient of aerodynamic of subsonic airfoil	nuimlabib	Main CFD Forum	3	July 4, 2009 10:17
Time accurate?	Steve	Main CFD Forum	2	March 25, 2008 08:39

August 5, 2010, 10:05		#2
niklas Super Moderator Niklas Nordin Join Date: Mar 2009 Location: Stockholm, Sweden Posts: 693 Rep Power: 29	and grid dependency?

August 5, 2010, 10:13		#3
aut_iut Member Rasoul Join Date: Feb 2010 Posts: 32 Rep Power: 16	Yes, of course! My initial grid is fine and refining the mesh just increases the solution time without any considerable improve to results. I also changed the divScheme in fvScheme file.