Low-cost field particle image velocimetry for quantifying environmental turbulence

Abstract

To date, there is a lack of in-situ turbulence data in natural aquatic systems. Adapting particle image velocimetry (PIV) to field use is of interest to provide such data. Past field PIV systems have been successful, but suffer from high costs, lack of portability, and flow disruption. We present a new field PIV system designed to address these limitations and capture turbulence metrics significant to aquatic biota: velocity, turbulent kinetic energy (TKE), vorticity, eddy size, and eddy circulation. Velocity measurements by the novel PIV system were compared to measurements by an acoustic doppler velocimeter (ADV) and an electromagnetic flowmeter for validation, and its results agreed with these other two methods. The PIV’s TKE results were compared to those of an ADV, and they agreed as well. Vorticity, eddy size, and eddy circulation were validated in the field through repeating past measurements. Each of these data sets generated by the novel PIV fell within the range of the validation measurements. The novel system thus provides accurate turbulence and velocity measurements; further, its design is low-cost, uses widely available materials, is minimally disruptive to the flow, and is highly portable and adjustable, offering an accessible method for acquiring meaningful field turbulence data.