1D-3D Coupled Simulation of Surge Waves in River-reservoir System by Using the Immersed Boundary-lattice Boltzmann Method

Many run-of-river hydropower stations located across the rivers with multiple channels have several powerhouses, owing to the separation by islets. In the transient process caused by sudden load rejection of one powerhouse, significant surge waves will appear in the channels and cause negative impacts on the stability of the operating hydropower units in other powerhouses. To simulate such surge waves in a reservoir and its connected rivers, and to depict the three-dimensional (3D) motion of waves near powerhouses and ship locks, a one- and three-dimensional (1D-3D) coupled model based on the immersed boundary-lattice Boltzmann (IB-LB) method is proposed. The 1D shallow water LB (SWLB) model is used to simulate the waves in rivers, and the 3D free-surface LB (FSLB) model is used to simulate the waves in the reservoir. These two LB models are coupled by applying water stage prediction and correction (WSPC), and the topography of the reservoir is handled by the IB method. To demonstrate the applicability of this model, we report the simulation of a practical example. The transient process is generated by an emergent load rejection of all units in one powerhouse, while the units in the other powerhouse are working with rated power output. It is found that the surge waves travel between different channels in the reservoir with regular fluctuating patterns. The histories of water level fluctuations and frequency spectrum analysis reveal the spreading and oscillating rules of the waves. This work demonstrates that the proposed coupled model has good prospects in engineering applications.