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# How to simulate a water filled bag with static pressure conditions

Legend

Hi,

I like to simulate a water filled bag without NX flow.

I want to create a bag as a bulky PSHELL structure (CQUAD4 / CQUAD8) with a solid inside representing water as a incompressible charge.

The structure has to be fixed i.e. at a complete perimeter edge.

Now I want to load the mesh i.e. with Gravity or external local pressure to get the deformation representing the influence of the constant inner volume of incompressible water.

Is that possible and what kind of solution I have to use?

I hope I could describe my problem in a sufficient way an wait therefore for answers.

Thanks. Michael

4 REPLIES

# Re: How to simulate a water filled bag with static pressure conditions

Solution Partner Genius

Hi Michael,

What is your expectation of the deformation of the bag? relatively large or small?

If small, then I think you can use hydrostatic pressure loading with Solution 101, without modeling the 3D mesh of the fluid inside the bag.

Regards,

Tuw

# Re: How to simulate a water filled bag with static pressure conditions

Legend

Hi Tuw, thank you for answering.

Since I want to describe a bag with a flexible bending behavior (poor bending stiffness but high membrane stiffness) I expect in my bag structure large local rotations and therefore also large displacements of partial sections of the bag.

First scenario: Imagine a bulky pillow made of thin tarpaulin, fully filled with incompressible liquid, lying at the ground, deformed by gravity.

I think the pillow will tend to flatten in vertical direction.  And in order to keep the inner volume steady it stretches in horizontal directions. Probably the size of the effect depends on the elasticity of the shell.

Second scenario: The deformed pillow will be loaded at one side with local pressure und the inner volume tends to dodge to all the other directions but has to stay constant and will providing an even inner pressure onto the bag. The difference of inner and outer pressure will be caught by membrane stresses in the shell of the bag and its local orientation.

That’s my problem. I hope I could make it clear to understand.

Could you give me further advices?

Thank you.

Michael

PS: What is a "kudo"?

# Re: How to simulate a water filled bag with static pressure conditions

Community Manager

A "kudo" is the same as a "like".

Regards,
Ganesh

Simcenter 3D Community Manager
Simulation and Test Solutions

# Re: How to simulate a water filled bag with static pressure conditions

Legend

Thanks for "Kudo" explanation. One "Kudo" for you :-)

But I am more interested in the real questions of this thread and all the answers I do not have yet.

Best regards, Michael