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Model the flow of a visco-elastic material

Posted 17.10.2014, 08:34 GMT-4 Fluid & Heat, Modeling Tools & Definitions, Parameters, Variables, & Functions, Structural Mechanics Version 4.4 2 Replies

Robin G.
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Hello,

I'm currently working on a model and i can't seem to tackle a few problems. If you would be so kind to help me out, I would be entirely grateful.

The model is a 2D section of the real 3D problem. There are 2 solid plates (rectangles). Between those 2 plates i have a visco-elastic material (also a rectangular shape) with in the center a rectangular gap. A pressure (10 bar) is put on the plates (top and bottem). Because of the pressure, the plates will practice a pressure on the visco-elastic material which cause it to flow to the gap.

I tried the following physics:

1) Fluid structure interaction : Used a moving mesh to let the fluid move inside the gap. I used a presdiscribed displacement in the form of U_fluid * time (time is defined). I get an error: failed to evaluate variable U_fluid.

2) Solid mechanics in combination with moving mesh and laminar flow: I used this as an alternative but I can't seem to define contact between the solid plates and the fluid.

3) Maybe I could define a visco-elastic material under the solid mechanics module. The only problem that I then have is that I can't seem to define flow.


Thanks in advance
2 Replies Last Post 24.10.2014, 03:18 GMT-4
Nagi Elabbasi Facebook Reality Labs
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Posted: 1 decade ago 23.10.2014, 18:47 GMT-4
Hi Robin,

Interesting problem, though I can’t fully visualize it. If the viscoelastic material deformation is not that big then option #3 would be suitable. In this case you don’t explicitly define “flow”. The viscoelastic material will just deform under a constant load.

Nagi Elabbasi
Veryst Engineering
Hi Robin, Interesting problem, though I can’t fully visualize it. If the viscoelastic material deformation is not that big then option #3 would be suitable. In this case you don’t explicitly define “flow”. The viscoelastic material will just deform under a constant load. Nagi Elabbasi Veryst Engineering
Robin G.
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Posted: 1 decade ago 24.10.2014, 03:18 GMT-4
Hello,

Thank you for your reply sir. I managed to get things working with fluid structure interaction. The problem was in fact a convergence problem. If I ramped up the pressure on the plate, I did get the results.

However I still have some questions left. If you or someone else would be so kind to answer them.

In your reply, you stated that you can model the deformation of a visco-elastic material and not the flow if the deformation is not large. However the deformations in this problem are large (up to 50%). From experimental results I also get a laminar profile. I don't see how the solid mechanics module could simulate a laminar profile (in terms of deformation).

Is it possible to get the same results if you work with the fluid-structure interaction or couple laminar flow with solid mechanics and moving mesh.

When I model the deformation of a plate in 3D or the same deformation of a section of this plate in 2D. I got totally different results. In my opinion I should get exactly the same results. How is it possible that I get a deformation in 3D that is 1000x less than the model in 2D.

Thanks in advance

RG


Hello, Thank you for your reply sir. I managed to get things working with fluid structure interaction. The problem was in fact a convergence problem. If I ramped up the pressure on the plate, I did get the results. However I still have some questions left. If you or someone else would be so kind to answer them. In your reply, you stated that you can model the deformation of a visco-elastic material and not the flow if the deformation is not large. However the deformations in this problem are large (up to 50%). From experimental results I also get a laminar profile. I don't see how the solid mechanics module could simulate a laminar profile (in terms of deformation). Is it possible to get the same results if you work with the fluid-structure interaction or couple laminar flow with solid mechanics and moving mesh. When I model the deformation of a plate in 3D or the same deformation of a section of this plate in 2D. I got totally different results. In my opinion I should get exactly the same results. How is it possible that I get a deformation in 3D that is 1000x less than the model in 2D. Thanks in advance RG

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