End-of-Fiscal Year (1991) Report
Abstract
The fundamental goal of this research is to investigate the limits to which both experimental and analytical descriptions of surface ship wake phenomena can be utilized to determine the hydrodynamic sources of the surface signature. Theoretical aspects of this research have concentrated on the solution of geophysical inverse problems. The extraction of ship information is based on the relations of the ship's wave spectra, wave amplitude function and hull geometry. In this research, an analytic representation of wave elevation is introduced with the use of the Hilbert transform, and the derivation is given for the calculation of the wave amplitude function from the Fourier spectrum of one and two dimensional complex-valued wave elevations. Methods and formulas are given for estimating a ship's speed and direction from the spectrum of a two- dimensional wave patch, a single wave cut or two wave cuts. A theoretical model of the wave amplitude function is developed, and three methods are designed for the estimation of a ship's length from the wave amplitude function. Under the assumption of thin-ship theory, an inversion technique to predict the geometry of a ship's hull from the wave amplitude function or its magnitude is developed through the application of a spectral method and the constrained maximum likelihood method. Examples comparing theoretically calculated data and tow tank experimental data are given to demonstrate the methods developed and estimated performance.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1991
- Accession Number
- ADA250986
Entities
People
- Robert F. Beck
Organizations
- University of Michigan