Bangor Hydrodynamics Laboratory
What is it?
The Hydrodynamics Laboratory of the School of Ocean Sciences is an experimental facility for the simulation of water and sediment movements by waves, tides, rivers and density currents. The 'Hydrolab' houses three experimental flumes and a range of instrumentation for measuring flow parameters and water quality.
The flumes...
The largest flume is 10 m long, 0.3 m wide, and 0.5 m deep. Water and sediment are recirculated by a Hidrostal screw centrifugal impeller pump that allows the passage of large solids and handles delicate material with minimum damage. A purposely made pipe system permits the generation of unidirectional, riverine flows and bidirectional tidal flows. The flume has a wave generator that produces regular water surface waves. The wave generator can be combined with the pump to produce combined flows. The flume has also been used to generate particle-laden density currents.
The smallest flume is 2 m long, 0.2m wide, and 0.14 m deep. This flume is particularly useful for studying erosional processes in cohesive and non-cohesive sediment.
The size of the third flume is in between the other two flumes, and it has a waterfall at its end, which has been used to study how effective plant roots are in stabilising sediment in salt marshes.
Large flume, looking in the direction of wave propagation. Wave generator on large flume.
Hidrostal pump on large flume. Small shear flume. The test section is 1.2 m long.
The instruments...
Ultrasonic Doppler Velocimetry is used to measure velocities in unidirectional and bidirectional flows. This method is tailor-made for high suspended sediment concentrations, where other methods fail to collect reliable data.
An Optical Backscatter probe is used to obtain concentrations of suspended sediment.
Wave gauges are available for measuring the height, length, period and propagation velocity of water surface waves.
Time-lapse cameras provide long time records of morphological change of, for example, sedimentary bedforms.
A high-end digital video camera is available for recording dynamic processes.
Ultrasonic Doppler Velocimetry probes.
What kind of research can be done?
The Hydrolab has been used for a wide range
of physical, biological and sedimentological research projects.
A small selection:
- The development of current ripples in biologically and physically cohesive cohesive sand
- Turbulence modulation in clay suspension flows
- The development of wave ripples in mixtures of sand and clay
- The flow of nutrient-rich and nutrient-poor water over mussel seed
- The stability of saltmarsh sediment as a function of plant root type, diversity and density
- The locomotion of fish
- Erosion around scale models of marine engineering structures
- Tidal bedform dynamics
- Critical bed shear stress of muddy sand
- Hydrodynamics and sedimentation of Sabellaria alveolata habitats
- Scallop gaping and effects of burial and sedimentation
- The effect of bypass flow asymmetry on the tuning of tidal turbines
- Fluid-sediment interaction in turbidity currents moving over soft muddy beds
Side view of current ripples in mixed sand-mud. Top view of poorly developed wave ripples in muddy sand.
Different types of interaction between turbidity currents and soft muddy substrates (based on work by Iris Verhagen).