Open channel hydraulics - lab

Experiment 1: Laminar flow table

• the dyes on the laminar flow table are indicative of the streamlines (streamline = a path defined by the motion of fluid elements in a flow; at any point along a streamline, the flow direction is tangent to the streamline. Conceptually, water may not cross streamlines.)
• the density of streamlines is proportional to the flow velocity
• observe and note the flow line patterns around the obstructions (Fig)
• is there evidence for turbulent flow  (Fig)
• what conclusion can you draw in terms of pressure and flow velocity, considering that Bernoulli's law is valid for this situation: u²/(2*g) + z +p/(r*g) = constant?
• where in the real world can you find situations like the ones shown here?

Experiment 2: Discharge measurements using control structures

• the height behind a weir is related to the discharge rate by the equations given below

• determine the geometry of the weir and measure the relevant parameters
• measure Q as a function of H for 5 different settings for one of the weirs  (Fig)
• enter the data in MS Excel and plot them up as discussed in class
• is Cd a constant or does it depend on Q?  (Fig)

• previous year's data (channel_lab_sum.xls)

• Thin Plate Weir Stage Discharge Relationships