The feasibility of performing particle-tracking-based flow measurements with acoustic cameras

Abstract

Abstract : Modern science lacks the capability to quantify flow velocity fields in turbid environments, particularly in the field. Existing optical-camera particle-tracking-based techniques developed to quantify two-dimensional (2D) velocity fields in laboratory environments, such as particle image velocimetry (PIV), are equipment intensive and can only be performed in a reasonably transparent fluid (so the camera can observe the light reflected by the particles). Acoustic-based flow measurement equipment used in the field (e.g., acoustic Doppler velocimeter and acoustic Doppler current profiler) can readily acquire velocities in turbid flows but only measure point velocities or velocities along a transect. Consequently, they do not provide the capability to quantify spatial gradients of velocity when deployed individually. The objective of this report is to explore whether acoustic cameras can be used in place of optical cameras in particle-tracking-based flow measurement techniques, such as PIV. Acoustic cameras may offer the capability to track a large number of particles in a plane as is required for traditional PIV and are designed to operate in turbid environments. The development of an acoustic camera particle-tracking-based flow measurement system will be able to quantify 2D flow velocity fields in turbid environments and be readily adaptable to a field-based system.