How I can measure the DRAG in any model of Fluent??

For instance a 3d Car model or in 3d wing

From the menu: Report -> Forces...

select all the surfaces of the car or wing (whatever you want to find the drag on) and select the vector direction of the drag force. So, if x points forward (where the car is going) then for drag you'd set the vector direction to:

x = -1

y = 0

z = 0

and the result is you get the component of the total force acting on the surfaces you selected - in the rear pointing direction - which is drag!

remember to set reference area in CD/CL calc and switch to correct reference velocity also

[MDinc]

I calculated drag force and coefficient in the same way that you have mentioned but I obtained 0.313 for 3D truck geometry. In literature, drag coef. value for truck is between 0.6-0.9. Furtherome, what is wrong with my calculations? I set the ref. values 20 m/s for velocity and 7.2 m2 for frontal area of truck. Also, what is CD/CL calc.for reference are that you mentioned in the last message?

Thanks,
Murat

[aamer]

Originally Posted by Jonathan Vogt
;149324

From the menu: Report -> Forces...

select all the surfaces of the car or wing (whatever you want to find the drag on) and select the vector direction of the drag force. So, if x points forward (where the car is going) then for drag you'd set the vector direction to:

x = -1

y = 0

z = 0

and the result is you get the component of the total force acting on the surfaces you selected - in the rear pointing direction - which is drag!

Dear Jonathan Vogt

its perfect to use X=-1, Y=0 and Z=0, to find drag on a car that is translating in positive X direction..... But how can we calculate drag for a car that is rotating about Y -axis...... (i.e initially it is aligned to +X axis and then during rotation it get aligned to +Z axis after rotating 90 degree and then it again gets realigned to +X axis after travelling another 90 degree...