This sediment transport teaching facility allows demonstration of the full range of bed forms 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. The equipment is portable, and therefore may be used in the classroom as well as in the laboratory.
The unit consists of an inclinable channel mounted on a frame, together with a discharge tank and re-circulating pump. To commence a demonstration, sand is placed evenly along the channel bed, between the inlet tank and the overall discharge weir. The channel slope is adjusted by means of a fine screw jack to which is attached an accurate slope indicator. The channel sides are transparent in order that bed profile changes can be readily observed.
Experiments
Fixed, smooth bed flow
Flow over a mobile sand-bed
Mechanics of sediment transport
Depositionary features and facies
Local scour
Flow structures
Bedform hysteresis
Computational work
Flow over a fixed, gravel bed
A water level gauge is supplied to measure the head over the channel discharge weir to deduce flow rates from a 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.
Features
Basic unit for flow-related experiments in open flumes1
Test section with transparent side walls
Superb Painted structure
Simple to operate & maintain
Utilities Required
Sediment diameter: 1 to 0.3mm
Weight of sand supplied: 15kg
First fill of water (approx. 22 litres)
Technical Data
Product & Code
Sediment transportation apparatus & HM-24
Channel working section
Length: 1.55m Width: 78mm Depth: 110mm
Discharge rate
3 fixed flow rates between 0.2 and 0.6 litres/sec, selected by switch on pump
Slope
0 to 4%
Shipping
Volume: 1m3, Gross weight: 150 kg
Overall dimensions
(l x b x h) 2.5 x 0.4 x1.1m (approx).
BEDFORMS IN SAND
As water flows over sand in a river or on a beach it exerts a shear force on the bed. If the flow is strong enough, sand grains are lifted to roll and bounce along the bed. The shape of the bed responds to this motion by transforming into ripples. As the energy of the flow and transport rate of sand increase, the bedforms change. Ripples are replaced by larger dunes.
At higher energy still, the dunes are washed out to produce a flat bed and in extremely energetic flows anti-dunes appear. Bedforms are important in affecting the flow of water and movement of sediment in rivers and on beaches. They also occur in deserts due to the movement of sand by the wind.
Bedforms are preserved when sand deposits are turned into sandstone by geological processes. They are used to reconstruct environments under which the sand was deposited.
