Effects of Geometric Shapes on the Hydrodynamics and Sediment Transport in Lateral Cavities

In riverine systems, lateral cavities are semi-enclosed volumes adjacent to the main channel flowing through its only opened side. These volumes play an important role in the mass transport processes, due to their higher residence time. The shape of the lateral cavity seems to influence the flow structure, although its effect on sediment transport remains unknown. In this study, numerical simulations ofthe flow past two lateral cavities of distinct shapes were performed to understand the impact of shape in the hydrodynamics and sediment transport. The 3D flow distribution was altered compared to the traditional rectangular shape by losing the secondary circulations near the wall. Moreover, the interface between the main channel and the cavity was a more uniform distribution of velocities in the upstream portion of the cavity with the change in shape. Furthermore, the shape did not influence the general behaviour of sediment transport, however, the peak of variables such as the Rouse and Shields numbers showed a difference of 6% and 135%, respectively.