In many real open channels there is sediment transport that affects the flow behaviour. Normally the key component is bed-load transport. HM 166 uses sand to demonstrate important phenomena of bed-load transport in the area near the bottom. The transparent experimental section allows observation of the formation of ripples in the river bed.
HM 166 consists of a circulating, oval, transparent flow channel. A deepening for holding the sediment in the longitudinal side of the channel forms the experimental section. The other longitudinal side contains a paddle wheel that produces the flow. A flow straightener at the inlet to the experimental section ensures low-turbulence flow.
The speed of the paddle can be adjusted in order to study how the flow velocity affects the bed-load transport. Flow velocities can be generated in the region of critical discharge (without sediment). The paddle is driven by an electric motor and a belt drive. Motor and speed adjustment are located under the base plate and are water resistant.
The fluvial obstacle mark, i.e. scour formation and siltation at bridge piers, is observed at three different pier models, which are inserted into the experimental section.