Learning Forum

[elissa el hajj]

Hello, I am tring to simulate air flow and acoustic sound pressure level inside a flute. I am attaching the picture for better understanding.
I would like to create an air flow through the flute and a pressure boundary condition on the enclosure like in the picture:

I would like to see what happens if there is a another air flow from the face of the solid flude inside of air enclosre.
fluent recognize that inlet named face as interface, so I can't change it to velocity inlet. I tried many things to manage that  air flow but no success..

I kindly ask how can I do that simulation?

also which model do you advise me to use? k-epsilon, k-omega, LES..?

[DrAmine]

One possible way will be to model the inflow as mass and momentum source in the cell layers near that "inlet" boundary. Or you separate a small region to be able to use inlet boundary condition.

For acoustic simulations you either need to use CAA so utilizie high end and scale resolving turbulence model (e.g. SBES) or you decouple acoustics from flow dyamics and use Lighthill acoustic analogy (Fowcs Williams Hawkings). However that anology is  not applicavle for enclosed spaces. When decoupling we still recommend Scales Resolving Methods but URANS can work too.

 

I recommend attending some training on Acoustic Modeling in Ansys Fluent.

[elissa el hajj]

Thank you for your reply. if I use k omega with acoustics on and set to broadband noise generation, will I get appropriate sound level pressure ?

[DrAmine]

For design purposes yes and actually it fits the quadrupole source noises so broad band. Tonal noise is more discrete and there you require high end models and to run transient too. With broadband you can aslo run steady. Fluent model includes several approximations which are case dependen Proudman for Broadband, TBL Noise for dipole, etc.. Check the documentation for more details..