Analysis and Comparison of the Behavior of Sediment in Bifurcations using Numerical Model with Physical Model

The main objective of the present investigation is to characterize the hydraulic and sedimentological behavior in different types of bifurcations of 90° with respect to the axis of the main channel and the direction of the water flow of the diversion channel, using the numerical simulation software Telemac Mascaret 2D (hydraulic behavior) and Sisyphe (sedimentological behavior), complementing and validating the results of these studies with the representation of two physical models of 90° bifurcation intakes investigated by Thoma.

This research allows us to optimize the design of intakes that directly capture the waters of a river without any storage structure, as a dam, avoiding the construction of diversion dams, because they have a high cost.

The recirculation zones are recognized, which reduce the effective width of a bifurcation affected by a contraction coefficient that shows the real space that the channel will take advantage, causing the passage of the flow to be affected by this zone and the material to be sedimented. This affects the discharge, decreasing downstream of the channel.

It was possible to model and visualize the behavior of the mentioned structures, concluding that it is feasible to use the numerical model as an indispensable tool for the design of this types of hydraulic structures.

The recirculation zone, present in the bifurcation in the described behaviors, is given as a recommendation to change the design of the bifurcation, from sharp edges to rounded edges, knowing that the rounded edges have a radius equal to 7 times the width of the bifurcation. Observing the elimination of the recirculation zones present at the entrance of the diversion channel formed by the abrupt change of direction of flow and the angle of 90° forming both channels, as well as the reduction of sediment levels in the main channel and the diversion channel.