ACOUSTICS AND STABILITY OF FLUID-FLOW IN A PERIODIC ELASTIC STRUCTURE

A fluid Bows horizontally through a fluid-structure system comprising alternating elastic solid and liquid constituents arranged periodicall y in the vertical direction. An exact analysis is performed to conside r the existence and stability of small acoustic waves and disturbances . The presence of the flow introduces the possibility of flow-induced Butter. Unstable waves are generally possible for M of order unity, M being the Mach number relative to the speed of shear waves in the soli d. Instabilities can appear for much lower values for antisymmetric fl exural type motion. In that case it is found that a critical wavenumbe r exists, indicating that the layered system is inherently unstable to long wavelength disturbances. (C) 1997 Academic Press Limited.