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How to use ANSYS CFX to get the drag coefficient?

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Old   September 24, 2005, 09:46
Default How to use ANSYS CFX to get the drag coefficient?
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victorzcc
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I used CFX to simulation a bluff body. CFX offers viscous force and pressure force,but it doesn't the coefficient. How can I get the coefficient of the bluff body? Please the master-hands help me! Thanks a lot!
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Old   September 24, 2005, 14:09
Default Re: How to use ANSYS CFX to get the drag coefficie
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Rui
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Hi,

In CFX-Post you can obtain force_x()@Surface, force_y()@Surface and force_z()@Surface.

If the velocity is aligned with the x-axis, you could obtain the drag coefficient as Cd = force_x()@Surface / (0.5*Rho*U^2*A)

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Old   October 7, 2005, 07:13
Default Re: How to use ANSYS CFX to get the drag coefficie
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victor
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Many thanks for you reply! Can you sent the tutorial of drag coefficient?
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Old   June 20, 2010, 06:05
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hi

to find drag coefficient, in the above formulae what is A,
is
A = length * width * 0.8
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Old   June 20, 2010, 06:22
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Glenn Horrocks
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A is a representative area. For bluff bodies that is usually the frontal area by for airfoils they frequently use the planform area. Check you use the right area definition.

But this is very basic stuff which is dicussed in most introductory fluid mechanics books. Go to your library and look it up.
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Old   January 23, 2012, 12:04
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Tom Walker
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I know this is quite an old post but I don't know where else to turn..

when I try and do force calculations in CFX i get an error message that says

"Only geometries with surface data
are allowed for calculating force"

what does this mean and how do I generate surface data?

Thanks

Tom Walker
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Old   January 23, 2012, 17:37
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It means exactly what it says - you can only calculate force on surfaces. You are trying to calculate force on a point, line or volume body and that is not meaningful.
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Old   January 23, 2012, 20:50
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thank you very much, I can't believe I was over thinking it like that!
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