Performance of Triangular Crested Weir under Impact of Sediment Deposition

【Objective】 Weir is a device to measure water flow in open channels. Its accuracy and robustness depend on many factors. In this paper, we studied the performance of the triangular crested weir as impacted by sediment deposition in open channels. 【Method】 The study was based on computational fluid dynamic modelling. We simulated water flow under nine conditions ranging from no sediment deposition to full sediment deposition using the software FLUENT 19.0. The simulated results were verified against experimental measurements. 【Result】 ①The simulation results were reliable and robust as comparison with experimental data showed that the simulated water flow rate and velocity distribution in the channels agreed well with those experimentally measured. ②When the theoretical flow rate was 0.221 0 L/s, the simulated and measured flow rates fluctuated erratically as the thickness of the sediment deposition increased, and the simulated flow water differed from the theoretical one with the difference varying from -0.45% to 8.60%. ③When the theoretical flow water was 0.221 0 L/s, comparison of the free-surface profiles with and without sediment deposition showed that the simulated and measured profiles occurred at different degrees of water level accumulation near the weir plate; the height of water level increased erratically with the increase in sediment deposition. 【Conclusion】 Comparison with experimental data showed that the simulation results are accurate and reliable. The water level in front of the weir rises because of the sediment deposition, and the flow capacity of the weir increases as a result. However, as the wire traditional formula does not have a correction term to account for sediment deposition, the flow rate estimated is smaller than the real ones.