Author(s): Busra Yildirim; Talia Ekin Tokyay

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Abstract: Groynes (spur dikes) are generally used to prevent bank erosion hence to avert any changes to river morphology. In this study, the effects of emerging permeable and impervious groynes over the flow are compared to an undisturbed flow field in a straight trapezoidal channel. A single groyne is located on one of the banks of the channel. The flow velocities are measured at several locations around the groyne. Particle tracking is applied to observe the fate of naturally buoyant particles in the presence of groynes in the flow field. The residence time of the particles is reported. In the simulations the permeable groyne is observed to allow passage of flow to the downstream side of the structure. The streamlines and the flow regime are less disturbed. Behind the impervious groyne strong turbulence is observed. This causes formation of a dead zone, which might affect the ecology in the channel. Shear stress maps over the channel floor are plotted at about a distance 5cm from the no-slip boundaries. Finally, two simulations using Volume of Fluid (VOF) method are conducted using unsteady RANS formulation to track free surface of the flow. These simulations are to investigate the changes in the free surface of the flow qualitatively in the presence of an impervious and a permeable groyne on one bank of a trapezoidal channel.

DOI:

Year: 2018