Learning Forum

[Pablo Sanchez Navarro]

Hello!

I would like to know whether it is possible to estimate the vibrations (Displacement vs. Frequency) of different flow rates inside a pipe. For instance, a 6mm ID pipe, 500mm long circuit and flow rate of 4, 5, 6 & 7 litres/min. How can we do this? Please give some details or examples if you can.

Many thanks,

Pablo

[Federico]

Hello Pablo, 

is this an acoustics simulation that you are looking to do?

If you're after the vibrations/displacement of the structure itself, you will need to couple your simulation with Mechanical.

[Pablo Sanchez Navarro]

Hi Federico,

This are some measurements of a similar system and we would like to estimate this before hand. There is Liquid Nitrogen running through the pipe and a heat source that is being cooled down. In a simpler scenario we have water instead and would be great if we can create similar charts in Ansys before running the experiments.

Many thanks, 

Pablo

[Federico]

You will need to set up a coupled simulation with Fluent and Mechanical.

You can find an example for fluid-structure interactions simulation here:

Analyzing FSI with ANSYS Fluent and Mechanical - Part I - YouTube

Analyzing Fluid Structure Interaction with ANSYS Fluent and Mechanical - Part II (19.0) - YouTube

[Pablo Sanchez Navarro]

Thanks Federico.

 

I think the problem I present here is way more complex in nature than that example. 

 

As you can see in the following video the inner flow doesn't show the eddies which are the main reason for the vibrations by a turbulent flow. I'm not convinced it is even possible to estimate the vibrations at those frequencies, the time steps would need to be ridiculously small and since they are influenced by the roughness of the inner pipe surface, I find hard to believe that ansys can give any meaningful data, to be honest.

Has someone tried solving a similar problem? Every video I have seen on YouTube focus on big events like a fluid hitting a big obstacle but nothing like the response from a turbulent flow at high frequencies. 

 

https://youtu.be/vUKhpbYcaqg?si=bV9VCjmonbOoH46v

Best Regards, 

Pablo