3D FREE SURFACE MODEL FOR A VERTICAL SLOT FISHWAY

摘要

The vertical slot fishway (VSF) is a hydraulic structure used to aid in the passage of fish past barriers to their natural migration. These barriers may consist of such structures as weirs, dams, culverts, and tidal barrages. This paper presents a computational fluid dynamics (CFD) model able to predict the three-dimensional (3D) flow within a VSF. The flow is typically characterised by a free surface with contractions, turbulence, and regions of high velocity and flow separation at the vertical slot jet. Also present within each fishway pool are distinct recirculation regions. The model solves the 3D Reynolds-Averaged Navier-Stokes (RANS) equations, closed with the re-normalised group (RNG) k-ε turbulence formulations. The model employs the volume of fluid (VOF) method to deal with the free surface. Verified results are presented for depth and velocity components, both internally from sectional planes and on the free surface of the model. Predictions of turbulence distributions are developed based on these validations. An important consequence is the ability to now deploy CFD methodology that is both efficient and fully predictive for hydraulic analysis of this fishway genre.