) is used when solving for the propagating modes used in a Port boundary condition in The Pressure Acoustics, Frequency Domain Interface. The study has special settings that can match the shape and wave number of the mode to a given port condition.) is used when solving for the propagating modes used in a Port boundary condition in The Pressure Acoustics, Frequency Domain Interface. The study has special settings that can match the shape and wave number of the mode to a given port condition.