[firsthero]

so i wanna simulate a rubber pump when it compresses and decompresses,
when it decompresses air goes in and when it compresses air goes out
it kinda looks like this 51uzrI2n9PL._AC_SL1000_.jpg

[vinerm]

Whether it is a fluid flow problem or not depends on the objective. What is the objective of the simulation?

[firsthero]

Originally Posted by vinerm

Whether it is a fluid flow problem or not depends on the objective. What is the objective of the simulation?

well the objective is to get the flowrate and pressure of the air using the pump, i have a design ready but i am not sure i want to send it here

[vinerm]

You don't need to send anything but without knowing about the aim, it is difficult to help. You can do this in CFD alone but since CFD does not solve for stresses and elasticity in solid material, you have to assign the motion yourself. Now, motion is not simple because it is a bellows pump. If you simplify it to a cylindrical shape, then motion is very easy, while with bellows, you have to put in some work to define motion of each surface. It is doable but you have to ensure that each surface moves as much as it should while inflating as well as deflating, else the system will break.

[firsthero]

Originally Posted by vinerm

You don't need to send anything but without knowing about the aim, it is difficult to help. You can do this in CFD alone but since CFD does not solve for stresses and elasticity in solid material, you have to assign the motion yourself. Now, motion is not simple because it is a bellows pump. If you simplify it to a cylindrical shape, then motion is very easy, while with bellows, you have to put in some work to define motion of each surface. It is doable but you have to ensure that each surface moves as much as it should while inflating as well as deflating, else the system will break.

and how do i do that exactly?

[vinerm]

If you do have some knowledge about fluid flow and Fluent, then it is not very difficult, however, if you have never used Fluent before, I'd suggest you do some simple tutorials before doing your own work otherwise it will be difficult to understand the implications of inputs and results.

[firsthero]

i have done fluent before, its the mechanical part and how to have the rubber moving is where i am stuck

[vinerm]

If you have used Fluent before, then it would be easier. Just start with a simpler, cylindrical shape with an inlet and an outlet or may be just an outlet if you want to study flow and pressure for only one stroke. You have to use layering option with one side moving towards the other side, just like piston in a cylinder. Once you have understood that, you can move on to understand how to define movement of bellows.

[firsthero]

ok thanks, but do you have any videos or anything i can follow?

[vinerm]

I don't but you will find a plenty online.

[firsthero]

i couldn't sadly, but thanks anyways

[vinerm]

That's because you may not have know the keywords to search for. Search using the following

layering method fluent

[firsthero]

thanks, but is that method only used for 2D? cuz all of the vids i found we're in 2D

[vinerm]

The method is same for 2D and 3D. The only requirement is that the mesh must be hexahedral in 3D and structured quad in 2D. So, you have to use sweep or multizone mesh, in case you use Ansys Meshing.

[firsthero]

ok thanks man, very much appreciated