Transient fluid-structure interaction in naval applications using the retarded potential method

Abstract

Submerged structures subjected to underwater shock remain a difficult and costly problem to analyze. In this work, the retarded potential (RP) method, which is a boundary element technique, is employed to discretize the fluid domain. The retarded potential program RPF is coupled to the ABAQUS non-linear finite element program to form ABAQUS/RPF. The Figueiredo method is used to convert the standard RP differential-delay equations for the fluid to simply delay equations, which are inherently more stable. ABAQUS/RPF is applied to both a rigid and elastic sphere. The Figueiredo approach is seen to extend significantly the stability range of the standard RP by a factor of approximately 10–20. Integration of the constant-pressure RP fluid element is shown to be very important to achieve this level of accuracy. Efforts to improve the Figueiredo approach using higher-order finite difference operators appear to have no effect on accuracy or stability. Stability of the coupled system is achieved by simply not extrapolating the structural accelerations.