Estimating turbulent kinetic energy with an acoustic Doppler current profiler

A new method for estimating turbulent kinetic energy (TKE) from acoustic Doppler current profiler (ADCP) measurements is presented. Current methods of estimating TKE from ADCP measurements require assumptions regarding the flow being measured. Combining the geometric orientation of ADCP sampling beams and the relative contributions of root mean square (RMS) velocities to the total TKE results in a formula that can be written for any ADCP. Data from a direct numerical simulation (DNS) are used with a virtual ADCP to assess the success of this method, and laboratory experiments are used to test the new method in a physical setting. The proposed approach measures TKE with an average RMS error of 15.2%, which is less than that from previous methods. Error caused by the ADCP sampling in different spatial locations contributes most to overall error; commercially available ADCPs typically sample at a high enough frequency and fine enough resolution to measure the RMS velocities needed to calculate TKE. Guidelines for measuring TKE with an ADCP are proposed, and published data on rivers are used to estimate the applicability of this method in practice.