Description: When acoustic perturbation occurs in a gas or liquid with high-speed underlying flow and the magnitude of the flow velocity is significant compared to the speed of sound in the fluid, the fluid will respond according to the well-known “Doppler effect.” The behavior of acoustic perturbation in a moving fluid can now be accounted for at the substructure and matrix generation level. This effect is best seen in models of tires where the velocity of the moving air is included in the dynamic analysis.