Learning Forum

[Hunter Dennison]

I've been having trouble finding the moments acting on a 2D body over time. The reason for this is that the body is part of a dynamic mesh in which its cg and placement in the fluid is moving. While its possible to do a coordinate transfer by placing the moment at 0,0 that is not preferred. I was wondering if there was a way to calculate the moments in accordance with the reference frame I set up as the body frame? Any help would greatly be appreciated. Also another thought is that I could try a rotating mesh that holds the body still, but that would require a lot of work to figure out given the nature of this problem (Object tumbling through air).

[Federico Alzamora Previtali]

Hello Hunter, 

the Moments will be applied on the center of gravity that you define in the Dynamic Mesh Zones dialog box for your body. As the CG moves over the course of your simulation, the application of the forces and moments will follow that motion accordingly.

 

I hope this helps

[Hunter Dennison]

That much I understand, but how would I go about extracting that from the 6DOF solver then? See what I'm looking for is to plot this moments as their corresponding coefficients such as pitch, yaw, and roll or just pitch in this 2D case. The problem is that I need these moments extracted for each timestep. However, I tried write motion history in the dynamic mesh settings, but it only gives me position, Euler angles, and velocity if I remember correctly. Therefore, my question is how can I plot these values when taken in the body frame or is that even possible without the use of my own coordinate transfer code in the current version of Fluent? So, sorry if that wasn't to clear when I posted this question at first.