Inadequacies of Piston Theory in Fluid-Shell Interactions

by Jerome M. Klosner, (M.ASCE), Prof. of Appl. Mech.; Polytechnic Inst. of Brooklyn, Brooklyn, NY,

Serial Information: Journal of the Engineering Mechanics Division, 1970, Vol. 96, Issue 2, Pg. 143-159

Document Type: Journal Paper


The results obtained from several exact solutions of the transient response of submerged cylindrical and spherical shells are presented. An analysis of these results points to the limitations of the plane (piston theory) and cylindrical wave acoustic approximations, and clarifies the reasons for their inadequacies. It is shown that when nonradiating components of the shell-fluid response are significant, the acoustic approximations are unable to describe the interaction phenomenon. Such components are significant when the motion of the structure induces closely spaced (when compared to the fluid wavelength) adjacent compressed and rarified regions in the fluid, which results in significant fluid flow along the shell. At high frequencies (short fluid wavelengths) this does not occur since sufficient time is not available. Although the relative simplicity of the acoustic approximations make them attractive, one should be wary of using them when it is suspected that closely spaced adjacent compressed and rarified regions are induced in the fluid.

Subject Headings: Fluid flow | Approximation methods | Wavelength | Compression | Transient response | Submerging | Cylindrical shells | Spherical shells

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