The impedance boundary condition (IBC) lies in between a traditional reflective boundary condition and a fully non-reflective boundary condition. There is no direct implementation of an impedance based wall boundary condition. However one. The soft walls where the acoustics wave are partially dampened /partially reflected are then modeled as velocity inlet with velocity equal to zero. On this inlet one can then use the impedance boundary. With zero velocity inlet there is not heat coming with convection. To disable heat diffusion one has to disable inlet diffusion in the energy equation. You can do this under the TUI: /define/models/energy then switch include diffusion at inlets? to no Keywords: Acoustic, Impedance, Wall, BC, Boundary,