Numerical modeling of submerged flow over ogee-weirs

Much research has been done on physical studies of submerged flow over ogee-crests in the past, yet there is not much research on how numerical models handle submerged or non-modular flow conditions. As numerical models are becoming more frequently used to model complex hydraulic systems, (e.g. spillways), it is becoming more important to understand how these models perform under specific conditions. This study reproduces physical flume experiments performed by Tullis & Neilson in 2008 and 2011 on a range of ogee-weir configurations. The commercially available Computational Fluid Dynamics (CFD) software Star ccm+ is utilized to build a Reynolds-Averaged Navier-Stoke (RANS) based numerical model. This study finds that a much finer spacing of the computational mesh were required to obtain good accuracy and mesh-independence for submerged flow conditions compared to free-flow conditions over the ogee-weir. With the finer mesh, the numerical model were able to reproduce data given in Tullis (2011) with good accuracy.