The modulation of short waves riding on non-uniform velocity fields (solitary waves and long waves)

• Main Author: Shen, Yifen
• Published: University of Edinburgh 1994
• Subjects: 530.1
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.661832

This work studies the modulation and kinematics of short waves riding on non-uniform velocity fields (solitary waves and long waves) and achieves theoretical and experimental conclusions. For the interactions between short waves and solitary waves, short waves and long waves, this research shows that the wavenumber, frequency and amplitude of short waves riding on solitary waves and long waves are strongly modulated. It also demonstrates that the maximum values of the modulated short wavenumber, frequency, and amplitude always occur at the crests of solitary waves and long waves. By increasing either the amplitude of solitary waves or the steepnesses of long waves the main conclusion--- that the modulated short wavenumber, frequency, and amplitude increase on the crest of solitary waves and long waves--- is achieved. The kinematics of two component waves (short waves and long waves) has been measured by PIV (Particle Image Velocimetry). Comparison of the results with Fourier theory and various stretching methods is also carried out. The mechanisms of the modulation of short waves riding on solitary waves or long waves, as studied in this thesis, provides a useful base line for work on more general and complex local water wave breaking.