Drag over Ahmed body

Shamoon Jamshed · May 18, 2009, 10:44

Hi all

I am simulating flow over Ahmed body in 2D. I want to calculate four drags front nose , the drag at the slant surface the back, the back drag and the total drag.

I want to ask that do I need to specify different reference area (or depth , I am not sure) for each of the drag values.

If yes, what reference area should I take. Remember that I am doing 2D!

N.B The values are not comparable with the standard graph of Drag coeffcients available for Ahmed body at different back angles!

Regards

Ralf Schmidt · May 18, 2009, 13:02

Hi!

check this out:

http://www.cfd-online.com/Forums/flu...hmed-body.html

For drag coefficient calculation, have a look inside the Fluent manual, how the area in 2D is calculated.

As far as I know, you have to set the reference area different for every value...

Just set different values and compute the coefficients... and you will see the influence...

Ralf

Shamoon Jamshed · May 18, 2009, 15:15

Well the mesh is structures. All the results, vel profile, stream lines are correct. The only problem is the area. In 2D I dont know how to specify the area for each individual wall!

Fluent manual didnot help

May 18, 2009, 10:44	Drag over Ahmed body	#1
Shamoon Jamshed Senior Member Shamoon Jamshed Join Date: Apr 2009 Location: Karachi Posts: 381 Rep Power: 18	Hi all I am simulating flow over Ahmed body in 2D. I want to calculate four drags front nose , the drag at the slant surface the back, the back drag and the total drag. I want to ask that do I need to specify different reference area (or depth , I am not sure) for each of the drag values. If yes, what reference area should I take. Remember that I am doing 2D! N.B The values are not comparable with the standard graph of Drag coeffcients available for Ahmed body at different back angles! Regards

May 18, 2009, 13:02		#2
Ralf Schmidt Member Ralf Schmidt Join Date: Mar 2009 Location: Austria Posts: 67 Rep Power: 17	Hi! check this out: http://www.cfd-online.com/Forums/flu...hmed-body.html For drag coefficient calculation, have a look inside the Fluent manual, how the area in 2D is calculated. As far as I know, you have to set the reference area different for every value... Just set different values and compute the coefficients... and you will see the influence... Ralf __________________ CFD - nothing but Colourful Fluid Dynamics

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May 18, 2009, 15:15		#3
Shamoon Jamshed Senior Member Shamoon Jamshed Join Date: Apr 2009 Location: Karachi Posts: 381 Rep Power: 18	Well the mesh is structures. All the results, vel profile, stream lines are correct. The only problem is the area. In 2D I dont know how to specify the area for each individual wall! Fluent manual didnot help