Laminar to Turbulent Flow in a Wide Open Channel

Theoretical equations are presented, involving the velocity and rate of laminar flow in rectangular channels and in channels of infinite width. Data taken at shallow depths on an open channel 1.5 ft wide and 20 ft long are plotted in a graph showing the relation between the friction factor and the Reynolds number. The point of departure of these data from the theoretical laminar flow line is taken to be the critical value of the Reynolds, Iiumber at which the flow changes from laminar to turbulent. A thread of dye was also injected into the flow to determine whether the flow was laminar, turbulent, or transitional. The two methods of determining the critical velocity gave similar results.