CFD investigation of a novel gabion-based porous medium configuration for energy dissipation in ogee spillway stilling basins

Ogee spillways which provide very large discharge rates are extensively employed for civil engineering applications, but high velocity flows generated by Ogee spillways can be seriously harmful to downstream structures. This numerical investigation is conducted to assess the potential of adding porous media (uniform gabions and cross shaped gabions, with varying porosities: 30%, 40% and 50%) to the stilling basin at the bottom of ogee spillways to dissipate energy. The maximum improvement in relative energy dissipation compared with the smooth-bed configuration reached approximately 65% for the uniform gabion configuration and 46% for the cross-shaped gabion configuration. In addition, the addition of porous media led to significantly low downstream Froude numbers as much as 91%–98%, showing the flow can be reduced from supercritical to subcritical flow regimes. Moreover, use of gabion based porous media provides a new cheap and hydraulic effective alternatives to the concrete stilling basins and their hydraulic efficiency can significantly contribute to construction cost saving.