Numerical comparison of the parameters influencing the turbulent flow using a T-shaped spur dike in a 90° bend

Spur dikes are used for river training purposes. To meet the navigability of rivers, the mean annual flow is considered; hence, in terms of river flooding, spur dikes are necessarily submerged. Considering the importance of submerged spur dikes, this paper studied the effects of a T-shaped spur dike’s submergence ratios on turbulent flow parameters in a 90° bend using the SSIIM as a commercial CFD model. The SSIIM numerical model solves the Navier-Stokes equations with the k- ε model on a three-dimensional, almost general, non-orthogonal grid. Submergence ratios of 0 (non-submerged), 5, 15, 25 and 50% were evaluated for parameters affecting the turbulent flow such as kinetic energy, pressure, eddy viscosity and the Froude number. It was observed that by increasing the spur dike submergence ratio from 0% (non-submerged) to 50%, in addition to changes in the values of pressure and kinetic energy, the Froude number changed in the bend and increased 2.1 times at the inner bank of the bend exit, and the eddy viscosity near the bed, which is the decisive factor of the turbulent flow, reduced by 42%. At the bed near the spur dike wing, the amount and range of kinetic energy reduced by increasing the submergence ratio. Near the bed, for all submergence ratios, the maximum pressure occurred at the upstream end of the spur dike.