[FSantoX]

Hey guys

I need to simulate a flow inside a pipe, but with the pipe vibrating in a manner that the channel opens and closes. The vibration is prescribed, I'm only interested in the effects on the fluid, not on the solid.

I wanted to know if it is possible on Star-CCM+. Also, the solid displacament should be very big, and I have no idea how that behaves with the mesh in a fluid simulation, regardless of the software.

Thing is, I can't find anything similar to that on the documentation. The closest one is the FSI tutorial, which doesn't really answer my question.

[Ubuntu]

Hi Fernando,

Do you have any pictures showing the motion of the pipe?
Are there any equations for the motion? (since you said you are imposing the motion on the pipe)
I may be able to help you.

[FSantoX]

Originally Posted by Ubuntu

Hi Fernando,

Do you have any pictures showing the motion of the pipe?
Are there any equations for the motion? (since you said you are imposing the motion on the pipe)
I may be able to help you.

Hello Siddharth

Thank you for your reply.

I made a quick sketch:https://imgur.com/0i3aiid

It's that, but in 3D. It is a circular pipe. That's not the complete domain, there is more, but that's the part I'm interested in discussing.

As for the movement, I would be using a table of values. I have the area ratio values with time, but not a time function.

[Ubuntu]

Originally Posted by FSantoX

Hello Siddharth
I made a quick sketch:https://imgur.com/0i3aiid

Based on this figure, I can suggest morphing motion in Star CCM+. I think there is a tutorial in User guide related to this.

Originally Posted by FSantoX

Hello Siddharth
As for the movement, I would be using a table of values. I have the area ratio values with time, but not a time function.

It can read table values and use for boundary conditions.

Hope this helps.

[FSantoX]

Originally Posted by Ubuntu

Based on this figure, I can suggest morphing motion in Star CCM+. I think there is a tutorial in User guide related to this.


It can read table values and use for boundary conditions.

Hope this helps.

I'll check this morphing motion today. I hadn't seen that term yet, but the name seems to imply exactly what I need.

I was already using tables, but for different boundary conditions. I just hope the table that I have will work with this condition.

One last question. With this problem, I need for the geometry to close off completely, but I think that could cause numerical issues. I've never worked with fluid-structure interaction before, but I've seen some papers that would not completely block the flow when solids were movind through the fluid. Can you tell me if it is possible to solve something like this? Or should I try to leave some minumum opening?

[Ubuntu]

Originally Posted by FSantoX

With this problem, I need for the geometry to close off completely, but I think that could cause numerical issues. I've never worked with fluid-structure interaction before, but I've seen some papers that would not completely block the flow when solids were movind through the fluid. Can you tell me if it is possible to solve something like this? Or should I try to leave some minumum opening?

I agree with you. I think that an attempt to close it completely will cause problems. The "negative volume error" is a usual one in case of morphing motion.
In my opinion it would be better to go for a minimum opening rather than trying to close it completely when you are using mesh morphing.

Also I have seen some videos (https://www.youtube.com/watch?v=RYKolUSipLQ) related overset meshing in Star CCM+ where it is possible to close the flow path completely. You can explore them too.

Hope this helps.