Flume for Teaching Spatially Varied Open-Channel Flow

Spatially varied flow in open channels is a topic that is often included in undergraduate open channel hydraulics courses. Physical and computational models are developed to enhance the presentation of spatially varied flow to engineering students at the late undergraduate or early graduate level. The physical model is inexpensive and easy to build and the computational model is easily developed using commercially available spreadsheet software. The physical model consists of a 30.48 cm nominal-diameter PVC pipe that is 6.1 m in length and has circular orifices approximately 1.40 cm in diameter drilled on 15.24 cm centers along the pipe invert. A relationship between the orifice discharge coefficient and a modification of the Froude number, as measured in the flume upstream of the orifice in question, was developed in repeated trials having varying flume slope, volumetric inflow rate, and end conditions. With this relationship, a stepwise solution to the energy equation is used to predict the water surface profile. Differences between the water surface profiles observed and predicted in repeated trials averaged approximately 2 mm.