shrinking of a tube
 

hello,
i have a problem and i cannot find a solution: i would like to shrink a tube in a dynamic way in fluent.
the pipe has a inner diamiter of 2mm and a lenght of 4mm. i want to obtain a diameter of 0.01 mm and then return to the original geometry in a dynamic way. i would like a continue continuous cycle of shrinking and regaining the initial geometry.

could you please help me?

Wow, that's too much for me. I would try a long pipe with different sections.

Conceptually, I think you have at least two options:

1. Use a UDF to induce mesh motion along the wall of your pipe that will contract and expand. The motion will be controlled by an equation that you will have to derive, and the coding can get a bit tricky.
2. Simulate a 1-way FSI in which the motion is driven by Mechanical, and Fluent just solves for the flow. This, while not difficult to setup, can get very advanced, so make sure you do your research and download some tutorials.

Good luck!
RD