Use of CFD for modelling spillway performance

This study presents the development of three independent models (two computational fluid dynamics (CFD) and one physical) representing the spillway arrangement at Stubden Impounding Reservoir. Beyond communication of the initial geometry (developed from a laser scan survey) all modelling was undertaken ‘blind’. The modelling results showed reasonable agreement for both reservoir rise (within 0·08 m) and also for the onset-location of a ‘check velocity’ on the spillway chute. For evaluating spillway performance, a well-constructed physical model to an appropriate scale and a well-developed CFD model, with a suitable mesh size, appropriate parameter settings, both with appropriate extents and boundary conditions can be expected to give very similar results (an overview of the benefits and drawbacks of both modelling techniques is presented and discussed).