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Shock and Vibration
Volume 8 (2001), Issue 2, Pages 105-122
http://dx.doi.org/10.1155/2001/853074

Computational Treatments of Cavitation Effects in Near-Free-Surface Underwater Shock Analysis

Michael A. Sprague and Thomas L. Geers

Center for Acoustics, Mechanics and Materials, Department of Mechanical Engineering, University of Colorado at Boulder, Boulder, CO 80309-0427, USA

Received 23 July 2001; Revised 23 July 2001

Copyright © 2001 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Fluid cavitation constitutes an expensive computational nuisance in underwater-shock response calculations for structures at or just below the free surface. In order to avoid the use of a large array of cavitating acoustic finite elements (CAFE), various wet-surface approximations have been proposed. This paper examines the performance of two such approximations by comparing results produced by them for 1-D canonical problems with corresponding results produced by more rigorous CAFE computations. It is found that the fundamental limitation of wet-surface approximations is their inability to capture fluid-accretion effects. As an alternative, truncated CAFE fluid meshes with plane-wave radiation boundaries are shown to give good results. In fact, a single layer of CAFE is found to be comparable in accuracy to the better of the wet-surface approximations. The paper concludes with an examination of variations in CAFE modeling.