Discussion Forum

Hi,

I've read that global equations will not accept position-based variables. Of course, calculating such integrals is no problem -- for some reason the just can't be put into a global equation.

So, if I have a definite integral (which seems to preclude the use of intOp since it can't take bounds), such as the integral from 0 to pi/2 of spf.T_stressy along part of a circular boundary, I can calculate that with a variable based on the integrate() function. But, I cannot then call that variable in a global equation. How can I get around this?

Also, perhaps I am not approaching this correctly at all (though knowing the answer to the above question would be useful regardless). The immediate problem is calculating the torque (or moment or shear stress or whatever -- I don't really care about the exact units -- I just need something appropriate to set to 0 in a global equation) created by a fluid acting on a circular boundary that moves within that fluid. I intended to do it by using sin and cos to sum the X and Y components of the stress at each angle. But, without being able to access definite integral results from a global equation, I can't figure out how to do this.

Note that the circular boundary has been defined as a moving wall, and while I'm not sure this is the problem, the normal structural mechanics forces that might be of use are all 0 (traction, reaction force, etc.), so this seems to constrain how I can approach the problem. I am purposefully not using the FSI module because this precludes treating the circle as a rigid body, in case that makes any difference.

Thanks,
James