Erik Kostson
Ansys Employee
Hi

We need to model the air and a box/enclosure surrounding the air which will be the pml region(share topology between them - see image below).


Then define physics region for both the PML box and the air (so two acoustic regions - see below), and the one for the PML enclosure set it to PML under the physics region settings (see below).

See below for details:
All the best

Erik