SPENDING BEACHES FOR A WAVE CANAL

Abstract

The principal obstacle to the production of a pure wave in a laboratory-wave canal of short length is the presence of a wave reflected from the down-stream extremity of the canal. Different artifices are used to reduce the value of the coefficient of reflexion. It is of important to see that these setups occupy as small a length of the canal as possible. We have undertaken the study of a simple mechanism, easily constructed, whose parameters can be defined rigourously and whose action is consequently consistent. The different parameters can be varied systematically so that the values which give a minimum coefficient of reflection for - given Incident wave can be determined. The mechanism consists of a spending beach made of a thin aluminium plate ; the plate has the same width as the wave-canal, its lines of greatest slope being parallel to the plane of symmetry of the canal.