Turbulent dissipation estimates from pulse coherent doppler instruments

Abstract

Utilizing a commercially available acoustic Doppler velocimeter, the Nortek Vectrino with optional plus (+) firmware, measurements of turbulence are made in a turbulent open channel flow in the 8m Research Flume of the DeFrees Hydraulics Laboratory. The measurements are used to estimate dissipation (ε) from Kolmogorov's 2/3, 5/3 and 4/5 Laws as well as integration of the dissipation spectrum. Corrections to remove bias due to Doppler noise are carried out when appropriate. Results from the four methods are compared to jusge the validity of each for use with single point velocity measuremnts from an acoustic Doppler Velocimeter. The 4/5 Law is the most consistent across each velocity component, but all methods produce reasonable estimates of dissipation from at least one velocity component.