Measurement of turbulence in a tidal channel using a laser Doppler velocimeter.
The results of a series of measurements of longitudinal velocity and temperature fluctuations made in a estuarine tidal channel flow are reported. A submersible laser Doppler velocimeter (LDV) operating in the dual beam forward scatter mode is used for velocity measurements. A dual differential amplifier photo-detector is employed to eliminate contamination of the Doppler signal by laser noise. The effects of a nonstationary mean velocity on the turbulent structure and the effects of stable temperature stratification ont eh velocity energy spectrum are examined. The authors evaluate the ability of the LDV probe to resolve turbulence in a geophysical flow at the high wave numbers which characterize the dissipation range of the energy spectrum. (A)