“…The theoretical fashions based totally on beam fashions mostly consist of the four-equation model, six-equation model, eight-equation model, twelve-equation model, and fourteen-equation model. These fashions are solely relevant for the lowfrequency acoustic conduct of linearly elastic, fluid-filled pipes of round cross-section [10]. An eight-equation mannequin approves for axial (longitudinal) and lateral (flexural) wave propagation alongside every pipe in the device [35,62].…”