SPH Energy Error

Ovunc

Hi, 

I am studying on the problem of fuel sloshing in the fuel tank while the car is moving on the road. I modeled the fuel with SPH. 

I kept some elements of the tank with RBE2 element. I moved the primary node of this RBE2 element with imposed displacement.

However, during the solution process, energy errors occur as %(-50), %(-30).

• I want to bring energy errors between - 15 percent and 15 percent. How can I bring energy errors into this range?
• Or are these error rates occurring due to the physics of the event?

Andy_20955

Hi,

The RBE2 element should work but I would suggest changing it to a /RBODY element.  /RBODY are used more often in Radioss. Take note that by default master node of the rigid body moves to the center of gravity of the rigid body.  This can be changed by setting the flag, Icog=3.

If you still get the high energy error, then I would suggest adding all your parts in /TH/PART and study the energy of the parts.  Are any parts gaining or loosing energy that looks wrong?  Also plot the global energy in the model and look at the contact energy, hourglassing energy,  TTE: Translational total energy, global Work. to see if anything looks abnormal. 

Thanks,

Andy