Application of laser doppler velocimetry to the study of turbulence generated by swell in the vicinity of walls or obstacles

Abstract

Swell develops an orbital motion of fluid particles, excluding any technique of measurement of the velocities using a material support, because the disturbance induced by the probe comes back to the point of measurement. Laser Doppler velocimetry allows a sharp measurement of instantaneous velocities and turbulence in fluid flows, without disturbing the movement of the fluid particles. Accordingly, we have adapted this technique so as to analyze: (1) the oscillatory boundary layer generated by swell on the sea-bed; and (2) the swell effect on structures. Our results impose restraints on certain modelizations.