Negative Volume problem in ALE model

Mark Lin
Mark Lin Altair Community Member
edited October 2020 in Community Q&A

Hello all

   

I am working a model which is a tank with water and air. 

image.png.849acd3cc3b87267a6417d43c4f0be4a.png

 

The Tank and Fluid impact to a rigid wall, and I want to see the stress of Tank and density of fluid.

The container is shell element and fluid were built by ALE.

 

The model seem fine when model check, but it generate negative volume problem quickly. (on fluid element)

 

image.png.e7d4bf91b91c7ad8475e0ddc0e4b2831.png

 

I don't know how to solve this issue, any option or suggest?      

    

 

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Answers

  • Crashphys
    Crashphys Altair Community Member
    edited May 2020

    There's a few kinematic issue in your model. I think the fact you are working on a skew is resulting in lots of pain, so if you can remake the model not in a skew, I would. I don't have much experience with rigid walls, but from what I can tell:

     

    - You did not set any skew for your velocity. I went ahead and change it so it moves in line with your created system.

    - You were constraining the whole model in the up/down direction while also applying gravity. I applied gravity on your model and constrained only the floor in the up/down direction.

    - I cannot figure out why the rigid wall has incompatible kinematic BCs. Perhaps someone else will be able to chime in on this. Make sure to review rigid walls and ensure you have implemented it correctly. Try running a tutorial with one first. Incompatible kinematic conditions means you have done something like apply motion and restrict it at the same time on a node or something.

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