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-   -   problem with cl and cd coeffients (http://www.cfd-online.com/Forums/fluent/106175-problem-cl-cd-coeffients.html)

nauman55 August 21, 2012 08:17

problem with cl and cd coeffients
 
hi i am doing a CFD analysis of blended wing body fuselage. i am facing problems in calculation of Cl and Cd of the fuselage. my cl and cd ratio at many angle of attack (up to 36 deg) are around 3. i am using the projected area along z axis for calculation and my geometry is in YZ plane. my all dimension are in meters. i am conducting analysis at mach 0.8 and 30000 feet altitude. need urgent guidance on this regard.
thanks

nauman55 August 21, 2012 08:40

addtions
 
my analysis is 3d and i m using SA model for the analysis.

cfd seeker August 22, 2012 02:29

Quote:

Originally Posted by nauman55 (Post 377984)
my analysis is 3d and i m using SA model for the analysis.

what problem you are facing? Your Cl and Cd values are not close to experimental values?

nauman55 August 22, 2012 02:55

re
 
no sir they are not matching with the wind tunnel test. like i am gettting Cl value of 0.35 and cd around 0.05. which i think are not correct.
regards

nauman55 August 22, 2012 03:05

one more query
 
sir the cl /cd ratio is around 3 at different angle of attacks. it is just a lifting fuselage not with out wings. moreover the cd calculated by fluent is total cd or some sub set of Cd?
regards

tapanshah001 August 22, 2012 07:12

check if ur CV is big enough...

cfd seeker August 22, 2012 07:41

Quote:

Originally Posted by nauman55 (Post 378098)
no sir they are not matching with the wind tunnel test. like i am gettting Cl value of 0.35 and cd around 0.05. which i think are not correct.
regards

what are the experimental values of Cl and Cd?
Quote:

moreover the cd calculated by fluent is total cd or some sub set of Cd?
Its total Cd


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