Learning Forum

[Caleb Wood]

Hello,

I have an LS-DYNA model which simulates the behaviour of a real-world wave tank. It is currently modelled as 2D but I plan to expand it to 3D once it is verified. Visually, the tank appears to function great (see image 1), however when you view the pressure distributions it is evident that it is not functioning as intended. I am trying to verify it against literature and the maximum pressure should be ~6,000 Pa, but my model gives values ranging to 20,000+ Pa when the piston on the left hand side begins to move, and the pressure distribution beneath the wave is not even (see image 2). Also, the moment the piston begins to move it sends a very high pressure wave across the bottom of the tank in a fraction of a second. If anyone has any insight on why this issue is occuring I would greatly appreciate your input.

Note that the piston and boundary particles are modelled as the same material as the water but they have constraints place onto them. Thank you.

IMAGE 1

IMAGE 2

[Loic Ivaldi]

Hello,

I don't use this modelling I use "real" part to make the tank like beam or shell and use 2D contacts. If you want to stay as you are try to add more layer of particles for the piston and the boundary. We can see on your first image a leakage of water.

What do you use to make the water ?

Best Regards,

Loïc

[Caleb Wood]

Thank you for the response, Loïc. I tried using shell elements and 2D contacts for the boundary conditions but ran into leakage issues. Have you ever ran into this issue before?

Also, my water is made of MAT_NULL and EOS_MURNAGHAN.

[Loic Ivaldi]

If you have leakage lower the TSSFAC. Also, maybe for the first runs try using *EOS_LINEAR_POLYNOMIAL for the water.

[Caleb Wood]

I will try that, thank you!