Drag Coeffient monitor very high

dwilson · December 1, 2012, 16:09

I am modeling a NACA 0012 in 2D. I have drawn the aerofoil and the freestream box in NX and imported the CAD in. I then set everything up and I have set up two monitors for Cl and Cd in order to compare them to experimental data.

The Cl I have is around 1.2 which is a little high but the Cd i have is -3 and should be around 0.2. I have no idea why this is. I have set the reference values correctly I think in the monitor section (1.177 for density ref pressure is 101325 velocity is 6.943 force option is pressure +shear and the direction is set to components 0.9848,0.1736,0 as the aerofoil is simulated to be at 10 degrees. I have been looking for ages as to why the drag might be so high as I cant see anything wrong.

any throughts?

nomad · December 4, 2012, 21:14

You should resolve forces in the streamwise(drag) and normal(lift) directions since your freestream is at an alpha.

niazaliahmed · December 21, 2012, 04:56

Hi try choosing Standard K-Epsilon Low Re with adequate mesh resolution near the wall...

December 1, 2012, 16:09	Drag Coeffient monitor very high	#1
dwilson New Member anonymous Join Date: Dec 2012 Posts: 3 Rep Power: 2	I am modeling a NACA 0012 in 2D. I have drawn the aerofoil and the freestream box in NX and imported the CAD in. I then set everything up and I have set up two monitors for Cl and Cd in order to compare them to experimental data. The Cl I have is around 1.2 which is a little high but the Cd i have is -3 and should be around 0.2. I have no idea why this is. I have set the reference values correctly I think in the monitor section (1.177 for density ref pressure is 101325 velocity is 6.943 force option is pressure +shear and the direction is set to components 0.9848,0.1736,0 as the aerofoil is simulated to be at 10 degrees. I have been looking for ages as to why the drag might be so high as I cant see anything wrong. any throughts?

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
drag coeff to high - kOmegaSST turbulence model	RugbyGandalf	OpenFOAM	5	February 22, 2011 02:35
high amount of drag coefficient. about 15????Is it okay?	ndabir	CFX	3	February 1, 2010 17:10
High drag coeff. estimated by Gambit+fluent	M. suuri	FLUENT	6	November 6, 2006 08:02
high drag value	sulfi	FLUENT	1	April 8, 2005 19:27
Multicomponent fluid	Andrea	CFX	2	October 11, 2004 05:12

December 4, 2012, 21:14		#2
nomad Member John Join Date: Aug 2009 Posts: 93 Rep Power: 5	You should resolve forces in the streamwise(drag) and normal(lift) directions since your freestream is at an alpha.

December 21, 2012, 04:56		#3
niazaliahmed New Member Niaz Ali Ahmed Join Date: Jun 2010 Posts: 13 Rep Power: 4	Hi try choosing Standard K-Epsilon Low Re with adequate mesh resolution near the wall...