Author(s): Yannick Marschall; George Constantinescu; Robert M. Boes And David F. Vetsch
Linked Author(s): George Constantinescu, Yannick Marschall
Keywords: Boulder array detached eddy simulation wake characteristics
Abstract: Replacing check dams and sills in mountainous regions by eco-friendly alternatives is of great interest. For rivers of slopes less than 3%, the placement of large, isolated boulders contributes to energy dissipation without hindering the migration of aquatic species. However, the knowledge about flow characteristics in arrays of boulders for close to critical flow conditions is limited. We conducted detached eddy simulation over a ramp with slope 2% and a staggered boulder array with two different boulder concentrations of 15% and 25%. The streamwise flow velocity and turbulent kinetic energy were averaged over the wake region of all boulders. The results reveal that only small regions of recirculating flow develop downstream of the boulders, which can be used by aquatic species to rest. However, for both cases the flow field is highly heterogeneous with high flow velocities above the boulder and high turbulent kinetic energy in the region of flow separation around the boulder. For both cases, the streamwise distance between boulders is too small for the flow to recover to a close-to-logarithmic velocity profile.
Year: 2025