6DOF problem
 

Hi, I'm trying to simulate a movement of a ball attached to a string in water free stream by 6ِDOF solver. According to equilibrium equations (has been attached) we know final position of the ball. I got correct answers in The X،Y plane My question is why I got a lot of movements in the Z direction
I will be grateful for any help


https://s6.uupload.ir/files/photo_20...qw08_thumb.jpg

https://s6.uupload.ir/files/inkedpho...xyw0_thumb.jpg