Figure 4
Three plausible models to place an elbow-flume in the wheel pits of the Barbegal complex with matching hydraulic models at right. Outflow water depth (Hf) and outflow flow speed (Vf) were calculated based on the geometries shown and the parameters given in the inset such as internal width of the flume (L), discharge (flow rate) in the flume Qf and roughness coefficient Ks, considering that the flow at the entrance of the flume is critical (Hinlet = Hc). Flow becomes supercritical in the flume. (a) Reconstruction of the elbow-flume in an undershot wheel model. (b) Reconstruction of the elbow-flume as a bypass that serves as outlet in an overshot model; (c) Overshot wheel models. Four hydraulic models are shown: for an inclined straight flume; a horizontal elbow-flume ending at the same level of − 0.2 m; and two elbow flumes with a slope of 3° and a counter slope of − 4°. These models show the effects of variation in shape and dip of a 2.1 m long flume for an overshot mill. Length indication refers to length along the bottom of the entire flume. For the top of the elbow flumes, the shape of segments E and R was used. Flow is supercritical in all cases, and the water height is lower than the critical depth Hc. For further explanation see text.
