Analytical and numerical investigations of linear and non-linear beam-water interaction systems

Zhao, Shenglin (2005) Analytical and numerical investigations of linear and non-linear beam-water interaction systems. University of Southampton, Doctoral Thesis.

Record type: Thesis (Doctoral)

Abstract

This thesis describes analytical and numerical studies of linear and nonlinear beam-water interaction problems. The mathematical model and analytical methods investigated, developed and the results derived provide a contribution to the study of the dynamics of beam-water interaction systems and the influence of modelling.

Natural characteristics and dynamic responses of linear beam-water interaction systems are investigated subject to an undisturbed or a Sommerfeld radiation condition imposed at infinity in the water domain. As a simple idealisation of a typical offshore structure, the influence of an attached mass with moment of inertia at the free end of the beam is discussed. The natural frequencies determined for the Sommerfeld condition are complex valued with real component values close to the corresponding natural frequencies for the undisturbed condition and the small imaginary components reflects a damping mechanism. That is, the imposition of this condition demonstrates energy dissipation in the system as indicated by the complex valued form of the natural frequency.

An iterative multi-block approach is developed to simulate the dynamic behaviour of nonlinear beam-water interaction systems using a computational fluid dynamics solver coupled to a structural dynamics solver. The selected combination cases involving linear/nonlinear springs and rigid/elastic beams are studied and compared. The results show that even for small movement, the flexibility of the structure is an important physical quantity in assessing the dynamic behaviour of the system.

Text

1014946.pdf - Version of Record

Available under License University of Southampton Thesis Licence.

Download (2MB)