A New Method for Measuring Flow Structure in the Benthic Boundary Layer Using an Acoustic Doppler Velocimeter

Abstract

A new system for precise measurement of vertical profiles of mean and turbulent flow structure immediately above the sediment?water interface is introduced. This system has an acoustic Doppler velocimeter (ADV) attached to an elevation system to allow for the precise measurement of the vertical profiles of three-component velocities in the range of 0.1?27 cm above the sediment surface in the field. This system enables an onboard operator to accurately measure height and move the ADV vertically to any point. The system was applied to in situ measurements of velocity profiles immediately above the sediment. The shear velocity, Reynolds stress value, roughness height, turbulent kinetic energy, and dissipation rate of turbulent energy were calculated and compared with often-cited values. The results showed the same flow properties as those from laboratory experiments and literature values. The advantages and disadvantages of the system are discussed.