F_AREA returns the wrong value

_Denis_ · August 26, 2011, 06:51

Hello, everyone!

Currently I'm running a multiphase axisymmetric problem. In order to calculate force on the floating body, I use following loop:

begin_f_loop(f,t){
F_AREA(A,f,t);
force[1] += A[1]*F_P(f,t);
}
end_f_loop(f,t)

But F_AREA macro is returning area vectors with much higher amplitude, than is possibly (my body is just not big enough), so, even without multiplying my results by 2*Pi, as I should, according to the manual, I get unnaturally big forces acting on my body.

Does anybody know how to fix it?
Thanks for your time!

_Denis_ · August 29, 2011, 03:00

What? No one encountered this problem before?

abhishekss123 · August 30, 2011, 08:37

F_AREA or C_VOLUME in axis symmetric should be multiplied by 2*pi - use (2 * M_PI)
Also make sure that your axis is coincident with X or Y axis... I suppose it can also cause troubles
hope this helps

_Denis_ · September 7, 2011, 09:30

I made sure that symmetry axis coinsides with Y, but this didn't help. I made my udf sum up the total area, and it's 5 times greater than expected.
Thank you for your reply, though.

August 26, 2011, 06:51	F_AREA returns the wrong value	#1
_Denis_ New Member Denis Join Date: May 2011 Posts: 17 Rep Power: 14	Hello, everyone! Currently I'm running a multiphase axisymmetric problem. In order to calculate force on the floating body, I use following loop: begin_f_loop(f,t){ F_AREA(A,f,t); force[1] += A[1]F_P(f,t); } end_f_loop(f,t) But F_AREA macro is returning area vectors with much higher amplitude, than is possibly (my body is just not big enough), so, even without multiplying my results by 2Pi, as I should, according to the manual, I get unnaturally big forces acting on my body. Does anybody know how to fix it? Thanks for your time! Last edited by _Denis_; August 29, 2011 at 02:58.

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August 29, 2011, 03:00		#2
_Denis_ New Member Denis Join Date: May 2011 Posts: 17 Rep Power: 14	What? No one encountered this problem before?

August 30, 2011, 08:37		#3
abhishekss123 New Member Abhishek Join Date: Sep 2010 Posts: 3 Rep Power: 15	F_AREA or C_VOLUME in axis symmetric should be multiplied by 2pi - use (2 M_PI) Also make sure that your axis is coincident with X or Y axis... I suppose it can also cause troubles hope this helps

September 7, 2011, 09:30		#4
_Denis_ New Member Denis Join Date: May 2011 Posts: 17 Rep Power: 14	I made sure that symmetry axis coinsides with Y, but this didn't help. I made my udf sum up the total area, and it's 5 times greater than expected. Thank you for your reply, though.