CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   FLUENT (http://www.cfd-online.com/Forums/fluent/)
-   -   calculating pressure force (http://www.cfd-online.com/Forums/fluent/108957-calculating-pressure-force.html)

 ramin3615 November 5, 2012 20:06

calculating pressure force

Hi
I have modeled stirred tank with four baffles.I want calculate torques on blades and cylinder walls manually.
the fluent option Force/moment get me good results but when i perform surface integration from this expression => -(static pressure*y)+(static pressure*x) to calculate pressure torque the values are quite different from what fluent itself give me but viscous torque that i calculated from shear stress integration was equal to fluent itself.
could anybody help me and tell me what to do?

 ramin3615 November 11, 2012 11:54

anybody help :confused:

 LuckyTran November 14, 2012 01:50

Probably your reference values are not set properly.

For the moment calculator to report the correct results: You need to provide the correct moment axis. Then you need to make sure the reference density, velocity, area, and length are set in the reference values task pane.

 ramin3615 November 14, 2012 04:21

hi Lucky Tran
thanks for your reply,i assume the pressure reference to be zero but i realy don't know the area and length reference values.my geometry is a stirred tank,cylinder radius is .025 meter with .06 meter hight and blades are .017 meter wide with .05 meter hight,blades rotates at 100 rpm so what are area,length and velocity reference values??:(
thank you in advance.

 ramin3615 November 14, 2012 04:28

i used zero operating pressure and assume the top open surface to be pressure inlet = 101325 pa.then i chenged the pressure reference value but it did not change.

 LuckyTran November 14, 2012 04:57

Sorry I may have told you the wrong thing. For the torque and moment calculator, you only need to specify the correct moment axis.

For the moment coefficients, you need to supply additional the reference values. I do not think you are trying to do this, so nevermind.

Double check your moment axis definition. I don't think anything else can go wrong.

 All times are GMT -4. The time now is 01:06.