三维溃坝洪水在复杂淹没区域演进的数值模拟

摘要

溃坝数值模拟为溃坝洪水的灾害性分析提供科学依据。针对溃坝洪水在复杂淹没区域中的演进过程，建立了耦合VOF法的三维k-ε紊流数学模型，采用等效糙率法处理了复杂下垫面，兼顾考虑了建筑物群的滞水及阻水作用。运用无结构贴体网格划分技术，建立了六面体单元网格模型。离散格式为二阶LUD空间离散格式和二阶Crank—Nicholson时间离散格式，并采用PISO算法进行了数值求解。通过Testa等人的物理模型的实验结果验证了该模型的准确性。结合东武仕水库溃坝在下游复杂淹没区域中的洪水演进过程进行了数值模拟和分析，并绘制了溃坝洪水风险图。%Numerical simulation of dam-break flood provides a scientific basis for dam-break disaster analysis. Coupled with the VOF method, a three-dimensional k-ε turbulence mathematical model was established for the dam-break flood routing in the complex inundation area. Considering the water-storage and the water-blocking roles of buildings, equivalent roughness method was used in the treatment of complex underlying surface. A mesh model of hexahedral grid elements was established by the use of the unstructured body-fitted grid technology. The discrete forms in space and time were the second-order LUD format and the second-order Crank-Nicholson format respectively, and PISO algorithm was employed. The accuracy of the model was verified by the experimental results of Testa and others. A simulation on Dongwushi reservoir dam-break flood routing in the downstream complex inundation areas was applied. The simulation results were analyzed, and the dam-break flood risk maps were made.