Waveguide Waves on the Water Surface in an Open Channel with an Built-in Source and a Capillary Wave Resonator

Abstract

Wave processes on the free surface of water in a channel are considered when semicylindrical capillary waves are excited by a source and a quarter-wave resonator inside the channel. It is shown that the experimentally detected accelerating surface flows on the water surface in channels with installed sources and resonators of semicylindrical capillary waves are associated with the excitation of waveguide waves in the channel. Waveguide waves with a distributed amplitude in the form of a standing wave are formed when semicylindrical capillary waves are excited in the section of the liquid surface in a channel. For capillary waves in the channel, the liquid surface is a waveguide open at both ends; waveguide waves are formed due to the reflection of part of the semicylindrical waves from the channel walls and their interference. Waveguide waves propagate after the waves emanating from the source with acceleration and produce an accelerating surface energy flow and, together with it, a surface flow of liquid due to the transfer of momentum to particles of the liquid. In contrast to semicylindrical waves, the front line of waveguide waves within the channel are straight like in plane waves, but the amplitude and intensity of these waves are maximal along the channel axis. The waves emanating from the source in subsequent periods of oscillations are superimposed on the flow produced by the waveguide waves and, as a result, their semicylindrical front lines are extended. The principle of generating an accelerating surface fluid flow by waveguide waves in a channel with a source and a capillary wave resonator can be used to produce acoustic flows in bounded media by sources of acoustic and ultrasonic semicylindrical and hemispherical waves. Using the same principle, it is possible to obtain directed flows of microwave electromagnetic energy in waveguides with open cavity ends by a source of semicylindrical waves inside the waveguide cavity.