Completed in 2008, the Aberdeen Open-Channel Facility consists of three components: a 23m long open channel flume; a motorized instrumental carriage; and a unique modular Particle Image Velocimetry (PIV) system. The combination of these three components form a world-class facility for studying smooth- and rough-bed hydrodynamics, sediment transport processes, flow-biota interactions and other aspects of fluvial and eco-hydraulics.
The open channel section of the flume is 1.18 m wide, 18.0m long and has glass sides and a glass bottom section to facilitate optically-based flow measurement techniques. Flume slope adjustment over a 3.0 degree range and a maximum flow rate of 150 l/s allow a large range of uniform flow conditions to be developed. The large width of the flume permits operation with large flow width to depth ratios, where the flow in the central part of the flume is statistically 2-dimensional and free from secondary currents and side wall effects. All aspects of flume operation are computer controlled, allowing precise and repeatable adjustment of flume slope, flow rate and flow depth.
A computer controlled instrumental carriage traverses the length of the flume at velocities up to 1.1 m/s allowing precise and convenient positioning of instrumentation and permitting ‘flying’ flow measurements which offer a unique perspective of the temporal evolution of turbulent eddy structures. The carriage carries three rackmount computers, instrumentation for measuring bed and water surface elevations, data logging equipment and a PIV system.
The PIV system developed for this facility consists of a pair of 100 Hz, 70 mJ/pulse Nd:YAG lasers, custom submersible laser optics, four cameras with 4 Megapixel resolution, and a direct to disk recording system with capability for over 60 minutes continuous recording. The PIV system can be configured for several operating modes: “panoramic” for large area flow field measurement (500x150 mm); “stereoscopic” for measuring all three components of the velocity vector; “3DPTV” for true three-dimensional measurements within a flow volume (150x100x15 mm); and “holographic” for high resolution measurements over a small fluid volume (15x15x15 mm).