Learning Forum

[maxning]

I am trying to find the pitching moment of a drone. After I run the Fluent calculation, I go and generated a force and moment report. The force is set for forces in the -Z direction and the force report output is this:

[Karthik Remella]

Hello It is printing the contributions of Pressure and Viscous forces to the overall moment. The total moment is the sum of pressure and viscous forces. It is also reporting the corresponding coefficients. The sign is indicating the direction of the moment. These coefficients are using the reference values in your case. You should be able to find additional information in our Theory guide here.
26.2.1. Computing Forces, Moments, and the Center of Pressure (ansys.com)
Regarding the second question - if these coordinates are representing the center of gravity in DM, then they should be the same in Fluent. You could draw a line passing through these points that is aligned with the axis of rotation in Fluent to verify. Please create this line as a post-processing element.
I hope this answers your question.
Karthik

[maxning]

Could you also tell me whether the positive and negative in the moment report means the moment is rotating in the clockwise or counterclockwise direction when we look in from the positive axis?

[Rob]

Use the right hand rule to figure that out.

[maxning]

I just don't know intepret the output and what they mean when the output have a negative sign.

[Rob]

Negative tends to mean reverse given it's a vector. So if you report a negative force in x the force is heading in -x direction. Moments are the same, but use the right hand rule to find which direction that is (clockwise is anticlockwise from the other side hence not using those terms).