基于弱耦合求解方法的排水管网底泥输运模拟

Numerical Simulation of Sewer Sediments Transport in Drainage Pipe Network Based on Weak Coupling Approach

摘要:

通过将SWMM（storm water management model）模型与底泥输运模型耦合计算实现对于排水管网底泥输运工况的模拟。利用该耦合求解方法，底泥输运过程对于管渠过流断面以及水流中污染物浓度的影响均可进行定量计算。耦合计算过程中全局时间步长由SWMM的时间步长确定，通过对底泥输运模型进行适当的调整使其适应SWMM时间步长，从而实现模拟的数值稳定性，避免了底泥输运模型出现过度沉积或过度冲刷引起数值不稳定的情况。该模拟方法通过2个案例进行了验证。通过案例的模拟结果可以看出该耦合过程可以给出稳定且合理的模拟结果，可以模拟管渠底泥的沉积及冲刷的过程以及其对于管渠过流断面及污染物浓度变化的影响。相较于单纯的SWMM模拟结果，耦合模型可以给出更加准确的模拟结果。

Abstract:

Sewer network hydraulic and quality simulation with consideration of sediment transport is conducted by coupling with the storm water management model (SWMM)with the sediment transport model (STM). Using this coupling model, the sediment load concentration and hydraulic cross section deformation of conduit caused by sediment transport in the sewer network can be quantitatively calculated. The global time step length of the coupling model is determined by the SWMM, and the STM is modified to adapt to the global time step so that the numerical stability in the simulation process can be achieved, and unsteady cases caused by over deposition and over flushing are avoided. The proposed coupling model was applied to two study cases, whose results show that this coupling model is stable and logical. The sediment flushing and deposition cycle and its impacts on load concentration and hydraulic cross section deformation of conduits can be simulated. Comparisons between simulation results and observed data indicate that the simulation results obtained by the proposed coupling process fit the observed data better than the simulation results without the coupling process.