Flow Channel Technical Description The unit is used to demonstrate flow over weirs and the streamlines around different drag models. A flow straightener at the inlet ensures low turbulence flow. Ink is injected into the flowing water using fine nozzles to visualise the flow patterns around the various models. 6 easy to interchange weirs and drag bodies can be placed in the channel. The height of the water in the channel can be regulated by adjusting the outlet orifice. The water supply is provided either from the laboratory (closed water circuit).