Finding the mode shapes at the outlet

Hello,

I am currently modelling a rectangular duct with the acoustics module. I am feeding various modeshapes e.g (1,0) (1,1) etc in the inlet via the port functionality and would ideally like to find what modeshapes come out downstream in the duct.

I have attempted modal analysis studies finding multiple modes in the outlet, yet this only gives the effective index value. I wonder is there a way of converting this into the modeshapes present e.g (1,0) or (2,0)? Is this even a function possible in COMSOL?

I saw this post using dispersion curves: https://uk.comsol.com/blogs/how-to-use-dispersion-curves-to-analyze-fluid-filled-pipes/?fbclid=IwAR1SrEapN4MJmnAOqUEr90PkxJ8CBdEEck__e0Sqoy4Dpe7589EI10zFt_4#goto-comments But I am unsure how to apply what is mentioned in my own models.

I wonder if anyone has had to do a similar analysis and has any pointers for me?

I would be really grateful for any help.

Thanks

Liam