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-   -   Sign convention when computing moments (http://www.cfd-online.com/Forums/fluent/112871-sign-convention-when-computing-moments.html)

Jeremie84 February 6, 2013 17:01

Sign convention when computing moments
 
Hi,

I would like to have more information about sign conventions in ANSYS Fluent regarding moments along an axis.

I am working on a vertical axis wind turbine, rotating along the Y axis. I'm using the Rotating Reference Frame approach (steady-state simulations). I used the right hand rule to determine the rotational velocity of the rotor: the rotation-axis direction is X=0;Y=1;Z=0 and I set a positive rotational velocity. After analysing the results, I am sure that the turbine is rotating in the correct direction. But, when I report the moment of the rotor along the +Y axis (I set the moment axis at X=0;Y=1;Z=0 in the Force Reports window), I get a negative value.

So my question is : What is the sign convention in Fluent when computing moments along a given axis? I would like to be sure that I misunderstood a sign convention before drawing any conclusions. Or does Fluent compute moments applied by the rotor on the fluid ???

Thank you

Regards,

Jeremie


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