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Description

The Armfield Sediment Transport Demonstration Channel enables the demonstration of the full range of bedforms that arise in a mobile bed as the flow and/or slope are increased.

The channel can be used to perform most of the experiments and demonstrations usually undertaken in much larger laboratory flumes, but at a much lower cost and without the need for technician back up.

The equipment is portable and therefore may be used in the classroom as well as in the laboratory. This demonstration flume can play a useful role in any course concerning the mechanics of open channel flow and sediment transport, including those in departments of civil engineering, geology and physical geography.

Sediment Transport Channel
The unit consists of an inclinable channel mounted on a frame, together with a discharge tank and recirculating pump. To commence a demonstration, sand is placed evenly along the channel bed, between the inlet tank and the overfall discharge weir. Water is circulated around the system at one of the three selectable flow rates. The channel slope is adjusted by means of a fine screw jack to which an accurate slope indicator is attached. The channel sides are transparent in order that bed profile changes can be observed and a section of one side is provided with graphical grid markings to permit quantitative assessments to be made of bedform dynamics.

A water level gauge is supplied to measure the head over the channel discharge weir to deduce flow rates from a user generated calibration chart.

Solid models of a bridge pier and an undershot weir are provided to demonstrate the scour effects on river beds of man-made structures.

Experimental Content

• Regimes of fixed bed flow
• Initiation of bedload motion
• Fixed, smooth bed flow
• Flow over a mobile sandbed
• Mechanics of sediment transport
• Investigate sediment transport rate and the relationship between the intensity of the flow and its ability to transport sediment
• Depositionary features
• Demonstrate scour at structures and study erosion effects associated with channel constrictions and flow around structures in the channel
• Flow structures
• Hysteresis of bedforms during changing stage
• Investigate flow resistance in a gravel bed and illustrate the difference between gravel bed flow and the sand bed flow