density currents

Subaqueous and subaerial currents with net deposition

These experiments use an inflow to transport sediment and build sedimentary deposits. Under the subaqeuous basin condition, the basin is filled with fresh water and a density current is generated using saline solution. Under the subaerial basin condition, fresh water is supplied to the basin.

Mixing salt-water solution for density current experiments

Common table salt (sodium chloride) is mixed with water to yield a high-density fluid for turbidity current experiments. A large tub is filled with water and bags of salt are added in 50 lb. (22 kg) increments. To dissolve the salt, a centrifugal pump is placed at the the bottom of the tub and is run for approximately one hour per bag of salt. To minimize corrosion, the pump is removed from the tub after use and submerged in a 5-gallon bucket of fresh water.

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SAFL density current basin

Basin for fluvial sediment transport experiments, including density currents. Two slope breaks in the basin favor sediment deposition, with a maximum accomodation space of approximately 5 cm. The bed slope is adjustable. Pumps are used to supply inflow and to control the water level.

Data acquisition options include overheard photos and topographic scanning.

Size: 4.0 m x 1.0 m x 0.5 m (length, width, height)

 

Steadiness of dilute, particle-laden density currents

We conducted experiments to examine how steadiness-unsteadiness of source parameters is reflected in density currents in air. We ran experiments with other wise steady supply broken by two intervals (e.g. 30-10-30-10-30, or 30-5-30-5-30, where currents were supplied for 3 intervals of 30 s separated by 10 or 5 second pauses). 

Particle-laden density currents in air

Currents are generated by loading a known mass of 20-micron talc onto a conveyor. The conveyor feeds the talk at a known rate into a chute. A portion of the talc falling down the chute forms a turbulent density current that enters the experimental "tank" (8.5 x 6.5 x 2.5 m enclosure). The current mass is determined by subtracting the mass of particles at the base of the chute from the initial mass loaded onto the conveyor.  Heated currents, for study of pyroclastic density currents, can be generated by loading the conveyor belt with heated particles.