Turbulent, discontinuous, open-channel flow: the contribution of Ralph Schröder

Abstract

Turbulent discontinuous open-channel flow appears in practice due to separation zones. The current practice overlooks the separation bubble by neglecting its velocity and by assuming static pressure on the active main stream. Based on the pioneering and so far unique work of Ralph Schröder, this approximation is compared with detailed computations of the energy and momentum velocity coefficients using his selected experiments. What would occur if their magnitude were 200 and 40 times greater than standard values? These extremes are demonstrated to occur and used to critically asses the “static bubble” approximation of roller flows. The data were also used to present generalized computations of the critical depth based on the energy and momentum equations, thereby proving that these differ in turbulent open-channel flow, although they are identical for potential flow. All these findings emerge from the outstanding experimental work of Schröder, which is critically reviewed to make his achievements available for the hydraulic community.