Scattering of Water Waves by a Pair of Semi-Infinite Barriers

Three-dimensional water waves are incident upon a pair of semi-infinite parallel vertical thin barriers. Assuming that the opening between the barriers is small compared with the incident wavelength, an asymptotic theory is developed for the resulting water motion. Between the barriers uniform progressive waves propagate into the channel. The transmission coefficient is found to be insensitive to the incident wave angle and the separation between the barriers.