A new type of horizontal submerged thin plate is introduced to focus wave energy in a certain place behind it. It is formed with a circular as well as elliptical curves not to cause a reflection of waves at the extreme edges of plate. It is termed as a crescent plate.
Some laboratory experiments are performed to identify the characteristics of the plate by applying a regular wave trains. Following major observation will be obtained.
(1) A crescent plate designed by the wave refraction theory can concentrate wave energy at a focal zone behind it in most cases, without wave breaking phenomenon.
(2) Maximum wave amplification coefficient 2. 7 was attained in present laboratory test.
(3) In certain cases, significant wave breaking occurs at the rear edge of plate. This phenomenon is frequently induced when the incident wave height becomes relatively high.
(4) Detailed numerical results by the Doublet Distribution Method agrees well with the experimental ones when the incident wave period is not large.
In any event, it is shown that a shape of crescent plate introduced in the present investigation can be easily designed by a simple design method based on the wave refraction theory and proved to be useful for efficiently concentrating wave energy with the increase of wave height.