Numerical investigation of flow in pool-and-weir fishways using a meshless particle method

A Lagrangian meshless particle method (moving particle semi-implicit method; MPS) has been widely applied to simulate engineering problems. In this study, a new solid boundary treatment using imaginary particles instead of traditionally predefined ghost particles is developed to accommodate sharp edges in addressing practical problems. The proposed solid boundary treatment in the weakly compressible MPS (WC-MPS) model is verified for a sharp-crested weir flow, and then applied to simulate flow in pool-and-weir fishways with thin walls, which can be considered as a flow system with a series of weirs. It was found that flow characteristics in pool-and-weir fishways can be determined for given design parameters such as pool length, height of weir, fishway bed slope, and water discharge. The plunging flow and skimming flow observed in experiments are reproduced successfully by the WC-MPS model. Simulated results demonstrate satisfactory agreement with experimental data.