fluid-solid interaction
 

Hi there!

Please could you let me know;
How is it possible to simulate a shape change of a not rigid solid inside a tube while the tube is filled with a moving fluid, should it be done through coupling ansys structure and fluent?, for cfd simulating which one is better in this case; fluent or CFX?, I think it is kind of fluid-solid interaction, right?

yes it is fsi. If boundaries are deforming due to liquid loads then it is 2 way and cfd and fea meshes need to deform (morph) or be replaced at time step intervals. For small deflections use CFX with ANSYS in WB which smooths the mesh or also use ICEM to supply modified replacement grids. Fluent ANSYS 2-way is only via MPCCI outside WB but allows full cavity remeshing using it's MDM capability to smooth or deform mesh.

Hi red-Lemon,
Thanks for reply,

would u Please kindly elaborate;

1. what is MPCCI, and is it easy to work with, as my deformation is quiet high, which the so-called mentioned Non rigid solid also could be considered kind of fluid with high high viscosity, i.e the solid deformation is so high,
2. I am asking to please kindly elaborate a bit more whole the story (in large deformation case) and let me know if there is any tutorial/reference for that,
3. Am I allowed to consider the solid as fluid with very very high viscosity and solve it as fluid –fluid via fluent by implementing VOF method,
4. Finally, just in case, if the deformation is not high, then u quoted “also use ICEM to supply modified replacement grids” , how could ICEM be used here, do u mean using it manually every time step to revise the mesh?

Thanks for the helps

1. what is MPCCI, and is it easy to work with, as my deformation is quiet high, which the so-called mentioned Non rigid solid also could be considered kind of fluid with high high viscosity, i.e the solid deformation is so high,
For large deformations you cannot get away with just smoothing so have to use Fluent with MPCCI or CFX with replacing meshes. MPCCI is a third party coupling service tool licensed by SCAI (not ANSYS) and allows many codes to hook up together.

2. I am asking to please kindly elaborate a bit more whole the story (in large deformation case) and let me know if there is any tutorial/reference for that,
There are many MDM tutorial cases available. check out the ANSYS customer portal or contact the support office to enroll on FSI or moving deforming mesh training

3. Am I allowed to consider the solid as fluid with very very high viscosity and solve it as fluid –fluid via fluent by implementing VOF method,
Yes that is one option but you may have to play with discretisation schemes at the boundary. Fluid-fluid will not bring along a default coupled wall at the interface.

4. Finally, just in case, if the deformation is not high, then u quoted “also use ICEM to supply modified replacement grids” , how could ICEM be used here, do u mean using it manually every time step to revise the mesh?
ICEM can be used to hook into CFX to move geometry and remesh then resupply to solver. If its not rigid body motion then probably not so useful here.

Many thanks for ur complete reply, could I ask u some other questions:

1. As I understand MPCCI can remesh by itself the domain even for large deformations for both fluid and solid,
2. My main question is fluid-fluid assumption which is currently my case,
Firstly I didn’t well understand this:” Fluid-fluid will not bring along a default coupled wall at the interface.”
And secondly in ur opinion how much is it reliable to consider non-rigid solid as fluid with very high viscosity?

Ur answers will really help me, thanks

oops! i have to revise my first question, i think u mean it is not possible to use the interface software to remesh in case of large deformation , so should I do it manually every time steps for solid and fluid phase?