Learning Forum

[Swapnil]

Hello, 

I am doing a two-way FSI simulation to capture the pressure wave through the deformable tube by keeping a constant pressure difference between inlet (left side) and the outlet (right side). But, I am not getting the desirable results. I have tried both strctured and unstructured grids but it still not worked. Does anyone have idea what could be the possible reasons for that?

[Rob]

If the dP is constant won't you just get a balloon effect? That looks like a Mechanical result, how are you modelling the fluid zone?

[Swapnil]

Yes it looks like a balloon effect. For structural part, I have kept both ends fixed. The fluid zone is inner core of deformable tube having dynamic mesh with smoothning and remeshing. Flow is laminar, incompressible with water as working fluid. At interface both solid and fluid zones are coupled.

[Rob]

Check materials etc. I did a demo case to highlight the first Fluent-Mechanical coupling in Workbench and finished up making the pipe out of (near enough) chocolate to get any meaningful deformation. You may also want to add a thread with the Mechanical settings into the Structures channel - as part of the demo I also managed to prove my complete lack of appreciation of the finer arts of modelling with the bendy solver! 

[Swapnil]

I tried with wide range of Youngs modulus and Poisson ratios (0.3 to 0.48). But could not get the desirable effect. What do you mean by "add a thread with the Mechanical settings into the Structures channel"?

AND

For fluid zone what could be the boundary condition at inlet/outlet, if not constant dp?

[Rob]

This is the Fluids (CFD) channel so we'd solve the fluid flow and then pass pressure over to Mechanical. So, inlet & outlet have a range of options. I also know next to nothing about modelling with Mechanical, so have no idea if a range of 0.3 to 0.48 is significant.