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-   -   DRAG CALCULATIONS (http://www.cfd-online.com/Forums/fluent/28268-drag-calculations.html)

Steve March 5, 2001 05:28

DRAG CALCULATIONS
 
Can anyone give me an idea of how Fluent goes about calculating drag (CD) values.

Is it possible in Fluent so look at the contributions of skin friction and pressure drag to overall drag, to see where my error is comming from?

Regards

Desmond March 11, 2001 05:32

Re: DRAG CALCULATIONS
 
Hi,

Fluent calculated the Cd values base on the following formula:

Cd=Fx/(0.5*density of fluid*mean velocity^2*projected area)

Fx was integrated by Fluent but the density of fluid, mean velocity and projected area has to be entered by your own in the reference menu. these values would not affect the model but just the force coefficients (Cd, Cl and Cm) reported by the software.

For Fx, it was contributed by pressure force and skin friction, you could see the value of Fx or force and moment at any specified direction or location by in the report menu. Force contribted by Pressure and friction would be listed separately.

Desmond

Ram March 16, 2001 13:44

Re: DRAG CALCULATIONS
 
Is there a provision to monitor the contributions (pressure and friction) separately?

Thanks

Desmond March 17, 2001 01:25

Re: DRAG CALCULATIONS
 
I think you could not "monitor" it by ploting the pressure and friction drag separately against no. of iteration during iteration, but what you could do is to stop by several iteration and stop to record the change of these 2 quantity manually.


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