PIV for Peanuts - a Low Cost Particle Image Velocimetry System to
Observe Terminal Velocity in Suspensions
Abstract
Particle Image Velocimetry (PIV) is a proven technique for the
observation of flow or particle motion in fluids. A pulsed laser is used
to create a thin plane of light in the fluid, which typically contains a
suspension of neutrally buoyant tracer particles. A high speed camera
captures a sequence of images, which are processed to develop velocity
vector fields from the particle motion. During a wider study into the
observation of particle and bubble terminal velocity in water using an
acoustic backscatter profiler in a recirculating sediment tower, the
acoustic data appeared to reveal a more complex flow regime than
expected. To verify the acoustic results, PIV was selected as a
potential approach to monitor particle motion in the region of the tank
where acoustic observations were being made. Review of available PIV
equipment showed that even systems designed for educational use would be
beyond the budget of the planned experimental program. A search of the
cupboards yielded an alternative set of equipment with potential
promise. A DIY laser level and an aging GoPro camera were pressed into
action for a series of tests to investigate whether the combined
equipment would be sufficiently sensitive and rapid to capture the
particle motion satisfactorily. It would. This paper describes the
equipment configuration and the range of measurements achieved. Results
from data processed with the open source PIVlab software tool are
presented in the context of validating acoustic measurements of particle
terminal velocity.