TRANSVERSE WAVES IN A CHANNEL WITH RECTANGULAR CROSS SECTION

Abstract

Transverse waves are interesting phenomena that occur in the direction parallel to the cross section of a channel when incident waves propagate along the water channel. They are studied in a channel with rectangular cross section 12 m long, 0.73 m wide and 0.90 m deep. Incident regular waves are generated by a computer-controlled piston-type wavemaker operating at one end of the channel and propagate away along the longitudinal direction of the channel. Transverse waves are found in the cross section when the wavelength of the incident wave is smaller than twice the channel width. Transverse waves, however, do not occur in the continuous mode but at some specific discrete frequencies. Different wave mode appears only when the channel width is an integer multiple of the half wavelength of the incident wave. By means of capacitance-type wave gauges placed in the water channel, the evolution of waves at different positions is recorded. Under the assumption of linear waves, the transfer function method based on the linear wave theory is employed to obtain the amplitude of transverse waves. Transverse waves with different mode number are observed in the channel and the mechanism and characteristics of transverse waves are discussed. Finally, the importance of transverse waves in the laboratory and in the natural environment as well as the relationship between original waves and transverse waves are discussed.