Improved analysis of regular gravity waves and coefficient of reflexion using one or two moving probes

This paper describes a complete spatio-temporal measurement of a set of regular waves propagating in a flume or a towing tank. This analysis is obtained by Doppler effect using the displacement of one or two moving free surface probes. The Doppler shift allows the separation of all the modes of the wave (incident, reflected, free and phase locked modes). This measurement includes for each mode the amplitude, the angular frequency, the wavenumber acid the reflexion coefficients; only a one-point probe moving at a constant speed is required. A highly accurate method is also described, using two one-point probes moving at the same speed but in opposite directions. The use of the one-probe method for a towing tank, where the platform transmits the motion, is straightforward. The two-probes method has a great interest for coastal engineering laboratory measurements. (C) 2000 Elsevier Science B.V. All rights reserved.