Improved Added Mass and Wet Modes Calculation for Naval Structures

PDF

Authors
  1. Smith, M.J.
Corporate Authors
Defence R&D Canada - Atlantic, Dartmouth NS (CAN)
Abstract
Several improvements have been made to the added mass and wet mode calculation modules in DRDC’s VAST finite element program. The performance of the improved software is described on the basis of accuracy and computational efficiency. For finite element models with approximately two thousand boundary elements on the wetted surface of the structure, the performance of the added mass computation module is improved by a factor of thirty. In larger problems the performance gain is even greater. Moreover, it is shown that these improvements are achieved without any loss of accuracy. Methods for predicting the natural vibration modes of floating or submerged naval structures are also reviewed. The dry mode approximation method is shown to be capable of calculating the low frequency wet modes with good accuracy and much better performance than a direct eigensolution of the wetted structure. The performance of the dry mode approximation has also been improved for large models. Finally, the VAST sparse solver is implemented for use in the direct eigensolution and dynamic response of wetted structures. The performance achieved with the sparse solver is shown to be significantly better than that obtained with VAST’s profile solver.

Il y a un résumé en français ici.

Keywords
Fluid added mass;Modal analysis;Boundary element method;Ship vibration;Complex Eigenproblem Solver
Report Number
DRDC-ATLANTIC-TM-2003-084 — Technical Memorandum
Date of publication
01 May 2003
Number of Pages
38
DSTKIM No
CA022948
CANDIS No
519966
Format(s):
CD ROM

Permanent link

Document 1 of 1

Date modified: