City Research Online

Abstract

The total wave induced loading on a vertical surface-piercing cylinder can be considered to be the sum of the linear drag and inertia components, and a number of second order forces. This study investigates the second order forces, both theoretically and experimentally. The second order waterline, dynamic pressure and Stokes' wave forces have each been shown to make a significant contribution to the theoretical wave loading under certain conditions.

In the experimental facility used, the wave environment was found to include a significant free second harmonic wave. This imposed an additional second order force on the test cylinder, which was dependent on the amplitude and phase of the free wave. An experimental technique has therefore been developed and used to deduce the amplitudes and phases of the individual waves present, from measured wave records. The wave results highlighted some important characteristics of the wave generator and flume.

The wave induced loading on the test cylinders has been measured, and analysed by means of a Fast Fourier Transform to separate the Fourier components of the force. The measured force components were compared with the theoretical forces calculated using the measured wave data. The first order force results were used to compute values for the drag and inertia coefficients. These were in reasonable accord with previous published results.

The theoretical second order force components were the sum
of a large number of forces, which could not be separated experimentally. Numerical comparison between the total theoretical second order force components and the measured results showed good agreement in a large number of cases. The agreement was less good in those cases where the theoretical forces were dominated by the free second harmonic wave. Recommendations are made for further experimentation under conditions in which the free wave amplitude is minimized.

Publication Type:	Thesis (Doctoral)
Subjects:	T Technology > TA Engineering (General). Civil engineering (General)
Departments:	School of Science & Technology > Engineering School of Science & Technology > School of Science & Technology Doctoral Theses Doctoral Theses

Export

Downloads