Erik Kostson
Ansys Employee

As we said for 3D use the coupled field transient system (2021 R2) that does not require any commands - it is all native:

For 2D we need pure transient system (see image below) then a command can be inserted under the acoustic body (like shown below), but you would need to change the properties as need so you need to learn some apdl commands (see apdl manual : et, matid, mp, keyopt,..).

!--snippet to be placed under the acoustic body --material prop. are for air so need changing---
et,matid,fluid29 ! fluid29 2D element
keyopt,matid,3,1 ! Axisymmetric

mp,dens,matid,1.2 ! density in SI units
mp,sonc,matid,343 ! speed of sound
mp,visc,matid,10E-4 ! visc.
r,matid,2E-5 ! reference pressure for exterior acoustics

I will close this post because we are going off topic in many ways and this is an Explicit forum.

Should you have any questions related not to Explicit products (like LS-Dyna and Explicit Dynamics), please post in the structure forum.

Thank you