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-   -   Resultant force magnitude and direction in CFX-post (http://www.cfd-online.com/Forums/cfx/63438-resultant-force-magnitude-direction-cfx-post.html)

 sohailgermany April 8, 2009 08:47

Resultant force magnitude and direction in CFX-post

Dear friends,
I have a cylindrical surface pressure distribution. I would like to find out the resultant force magnitude and direction due to the pressure on that surface. How to do it in CFX-Post?. What is the difference between the following two approaches:

1. Function: AreaInt (Variable: Pressure) at the selected location in a certain direction
2. Function: Areaavg(Variable: Force) at the selected location

I think, they both should give same answer, but they are not. Perhaps, I am not understanding it right. It would be great help, if someone explain the difference between them.
Thank you.

 ghorrocks April 8, 2009 20:31

Hi,

The area integral of pressure does not include wall shear. The best way to get the total force on a surface is using the force_x()@Surface command.

Glenn Horrocks

 abhishekchitvar March 19, 2013 04:52

Regading the same problem as discuss above.

Hello All,
Greetings!

@Mr. Glenn Horrocks ; How to find the location of the resultant force using the geometry and pressure distribution?:p

 ghorrocks March 19, 2013 05:29

You can calculate it from the force_x() and torque commands. I will leave the derivation of the equations up to you - here's a hint.... torque = force x distance.

 abhishekchitvar March 19, 2013 08:11

Hello Mr.Glenn Horrocks,

Thanks for quick reply and suggestion.

However, It's not solve our purpose. We have annular cavity with some thickness, we find out the pressure distribution over inner and outer surface.
also calculate the forces in YZ plane and length in X-direction. Using this we have calculate resutant force and angle. But we could not have idea to find the location i.e x distance, in X-direction i.e axially.

As your suggested that calculate torque and then using this it would be possible to calculate the distance. However, the CFX gives the torque in y and z direction too. but we don't have constraint to our geometry.

If you have more views on the same, Let me know.

Thanking you!:o

 singer1812 March 19, 2013 09:52

Resultant force location is not unique. It is a vector. Fix one of your points (perhaps on your body) and the other points will fall out.

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