Title page for ETD etd-04212009-223310


Type of Document Dissertation
Author Klenow, Bradley
URN etd-04212009-223310
Title Finite and Spectral Element Methods for Modeling Far-Field Underwater Explosion Effects on Ships
Degree PhD
Department Aerospace and Ocean Engineering
Advisory Committee
Advisor Name Title
Brown, Alan J. Committee Chair
Batra, Romesh C. Committee Member
Hughes, Owen F. Committee Member
Kapania, Rakesh K. Committee Member
Keywords
  • spectral element method
  • finite element method
  • cavitation
  • underwater explosion
Date of Defense 2009-04-08
Availability restricted
Abstract

The far-field underwater explosion (UNDEX) problem is a complicated problem dominated by two phenomena: the shock wave traveling through the fluid and the cavitation in the fluid. Both of these phenomena have a significant effect on the loading of ship structures subjected to UNDEX.

An approach to numerically modeling these effects in the fluid and coupling to a structural model is using cavitating acoustic finite elements (CAFE) and more recently cavitating acoustic spectral elements (CASE). The use of spectral elements in CASE has shown to offer the greater accuracy and reduced computational expense when compared to traditional finite elements. However, spectral elements also increase spurious oscillations in both the fluid and structural response.

This dissertation investigates the application of CAFE, CASE, and a possible improvement to CAFE in the form of a finite element flux-corrected transport algorithm, to the far-field UNDEX problem by solving a set of simplified UNDEX problems. Specifically we examine the effect of increased oscillations on structural response and the effect of errors in cavitation capture on the structural response which have not been thoroughly explored in previous work.

The main contributions of this work are a demonstration of the problem dependency of increased oscillations in the structural response when applying the CASE methodology, the demonstration of how the sensitivity of errors in the structural response changes with changes in the structural model, a detailed explanation of how error in cavitation capture influences the structural response, and a demonstration of the need to accurately capture the shape and magnitude of cavitation regions in the fluid in order to obtain accurate structural response results.

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