Coupled Eulerian Lagrangian (CEL) analysis for fluid flow?

[gaetano89]

Hello,

I am working on FSI analysis and due to extreme deformation of the structure, the usual Abaqus CFD/Explicit co-simulation, is not good enough anymore. For this reason, I was looking into FSI by using CEL analysis.
Looking at some videos online, it seems possible to use CEL for fluid flow analysis (let's say a simple fluid flowing in a channel). Unfortunatelly I'm not able to understand how to apply boundary conditions to the model.

How can apply an velocity to an inlet? Should I do it to the Lagrangian mesh or to the Eulerian? Since the Eulerian mesh follows the material rather than the nodes, is it possible to run steady-state analysis?

I hope you can help me

Thanks
G

 

[IceBreakerSours]

Getting a 'good' CEL model is a several weeks, if not months, long adventure. Before I answer your questions about CEL, I want to know why it is that a CFD simulation is not good enough? How do you define good enough? And what makes you think CEL route will lead you to your goal.


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[gaetano89]

Hi!

Yes I can see that it takes very long time!! I can not use CFD anymore because I'm working of the fluid influence on a morphing structure. This structure involves two initially independent elements that, thanks to the aerodynamics loads, will then become one element. Now the CFD model is basically a block of fluid with holes in it which represent the structures analysed in the Abaqus explicit model. If this structures need to be in contact at one point, the mesh of the CFD model will collapse and of course the analysis aborts...

While witht he CEL I won't have this problem anymore (see the example of the peristaltic pump you can find on youtube).

Do you have any tips on how can I run a fluid flow with CEL analysis?

Thank you a lot
G

 

[Dave442]

Hi,

There are some simple examples of CEL analyses with fluid-structure interaction in the documentation:

"Deflection of an elastic dam under water pressure" in the Abaqus Benchmarks Guide would be a good place to start.

From your description it sounds like the Eulerian mesh would represent your fluid domain while the Lagrangian mesh would represent your solid domain(s). To define the fluid behavior you need to specify inlet/outlet/wall conditions for the Eulerian mesh like you would in a typical CFD analysis.

As you're working on an aerodynamic problem, you should note that CEL is not structured like a CFD code. While it does include viscous effects with extension to laminar flows, I do not think you can include any turbulence effects. If turbulence is prominent in your problem you may struggle to achieve validation.

Good Luck,
Dave

 

[gaetano89]

Hi Dave,
Thanks a lot for your answer. I cannot use turbulence, but I can use compressible fluids! My problem with CEL is actually how to set the boundary conditions. If I want to simulate a simple fluid flowing in a channel how should I set my analysis?
Do I have to create a very long Eulerian channel and then another part which represents my fluid which will flow through the eulerian part?
Can I not just have an Eulerian part and apply inlet outlet and wall conditions as it was a normal CFD problem? If it is possible, and I tried, how can I do?
thanks again!