A comparison of 2D and 3D simulations of the River Blackwater

The present paper reports the findings of a study in which the appropriateness of using two-dimensional (2D) and three-dimensional (3D) numerical modelling in order to simulate the flow in a small reach of the river Blackwater, UK, was examined. The numerical simulations were compared with data obtained from a 1 : 5 scale physical model of the reach. A variety of turbulence models were used in order to evaluate their suitability and assess their impact on the simulations. In order to enable direct comparisons, all of the simulations were undertaken using a single modelling code, Delft3D. It was shown that 3D models offer significant advantages over 2D when applied to a meandering channel and that this choice outweighs the choice of turbulence model.