Effects of Multi-Point Distributed Hydrodynamic Regulation Using a Flapping-Hydrofoil Biomimetic Pump on Water Quality

The plain river network is characterized by low and flat terrain and a complex structure, resulting in slow water exchange and weak hydrodynamic conditions. To address these issues, a flapping-hydrofoil water pump driven by composite harmonic motion is proposed to promote water flow. First, a computational model for the flapping hydrofoil is established based on the finite volume method (FVM) and overlapping dynamic mesh technology. Five different distributed motion schemes for the flapping-hydrofoil devices at various points are selected, and the hydrodynamic performance of each scheme is computed to establish the corresponding relationship with water flow. Next, the river network of the Nanxun District in the Taihu Lake Basin is taken as the study area. A MIKE21 two-dimensional hydrodynamic-water quality model for river networks is constructed, where water flow is used as a variable factor. The objective function focuses on minimizing energy consumption under different motion schemes. The model is used to simulate and analyze the flow field distribution and water quality changes under different scenarios, aiming to explore optimization scheduling methods for enhancing hydrodynamics and improving water quality in the river network of the study area. The results show that, compared to the five motion schemes, the propulsion efficiency is maximized in Scheme IV, with a value of 49.34%. This represents a 1.12-fold increase in water propulsion efficiency compared to Scheme I (single flapping-hydrofoil motion). However, considering the water quality improvement, Scheme I exhibits the best effect in terms of flow increment. Under the conditions of Scheme I, the BOD (Biochemical Oxygen Demand) removal rate at the reference point 2 area reaches 40.94%, and the DO (Dissolved Oxygen) concentration improvement rate reaches 1.78 times.