Laboratory Analysis of Momentum-Induced Chokes in Free Surface Flow

The laboratory exercise described herein allows undergraduate fluid mechanics students to observe and perform experiments on an interesting and pertinent free surface flow phenomenon. A momentum-induced choke is created when lateral inflow enters a hydraulically steep channel at a volumetric rate that is sufficient to induce a choke condition. The choke condition creates a hydraulic jump that may move upstream and drown the channel inlet section. This situation can occur at inlets in storm sewer systems. The project requires students to derive an analytical equation giving the critical lateral inflow rate as a function of approach flow conditions. They also perform a series of flume experiments that produce empirical data for comparison with the theoretical equation.