## LS Dyna

#### Accounting for Movement of Fluid in Drop Test and Volume Change

• morganj32
Subscriber

Good afternoon,

I am trying to simulate the drop test of a tank, 80% full with water, onto one of its corners. The purpose of the test is to determine if a cap over the fill hole will fail. The location of the cap could be in four different positions depending which corner the tank is dropped onto but for the first instance I am assuming it is where the red dot is on the picture of the geometry below. The tank itself has already been tested and elsewhere so its actual behavior is not of concern, the cap is the focus.

If the cap is to fail, I am unsure if it will be because of the water splashing up from the impact with the floor and hitting the underside of the camp or because of an increase in pressure in the tank caused by deformation when it hits the floor.

I have am having problems with both of these methods:

1. I do not know how to simulate the water in the tank so it splashes upwards to investigate it hitting where the cap would be.
2. I cannot find how to get the volume change of the tank caused by the deformation upon impact.

So far I have tried simulations in both explicit dynamics and transient structural with the transient one being what I believe is most representative. I have applied atmospheric pressure to the interior faces of the tank not filled with water and I have modelled water as an orthotropic solid based on this analysis by @peteroznewman but I am unsure if that is a fair assumption in this case. Then I have given the tank a downward velocity and gravitational acceleration and fixed the floor.

Any help would be greatly appreciated and thank you in advance.

• Chris Quan
Ansys Employee
Please refer to the Workshop #2 in Autodyn Training Course: Drop Test of Filled Container. nAttached pictures show the material motion of air and water inside the container at the beginning of the drop impact and in the middle of the impact.nBe aware that multi-material Euler solver can be activated in Explicit Dynamics system with valid Mechanical Enterprise license when the Reference Frame is set to Virtual Eulerian.nThe materials Air and water can be modelled in virtual Eulerian frame to better simulate their large motion, splashes, and the interaction with the surrounding solid containers (bottles).nnnnn
• morganj32
Subscriber
thank you for your answer.nI have followed the workshop and got close to what I wanted however I think there are a couple of issues still and I would like some help with them if possible.nWhen looking at the total deformation of the bodies it looks like the fluids move separately to the tank body and come out of the top of it as shown in the picture below. I want the fluids to be within the tank and move with it, do you know how I can do this? I have tried adding contact bodies but so far this has not worked - the version in the picture below uses no contact bodies as specified in the workshop. nThanks once again. nn
• morganj32
Subscriber
Is anyone else able to help with this?n