基于精细地形建模的溃坝洪水演进三维数值模拟

Three-dimensional numerical simulation of dam-break flood routing based on fine terrain modeling

针对三维溃坝洪水数值模拟缺乏涉及城市复杂下垫面地形建模的水库溃坝洪水演进的研究现状,本文首先提出了基于TIN与NURBS曲面重构的精细地形建模方法,同时结合等效糙率法以区分不同的下垫面条件对洪水的水流运动产生的阻力影响,从而为溃坝洪水演进三维数值模拟提供精细的下垫面信息;其次,采用耦合VOF法的修正RNG k-ε湍流模型模拟了溃坝洪水的演进过程,并通过模型验证分析了该模型的准确性;最后,以某城市地区水库溃坝为例,分析了下游复杂区域洪水演进过程、流速、水深等水情信息。结果表明:本文提出的地形建模方法具有较小的数据储存量且保持较高的地形精度;同时基于精细地形建模的溃坝洪水演进三维数值模拟既准确地模拟了洪水演进过程,且充分地反映了溃坝水流的复杂流态及细节。

Previous three-dimensional numerical simulations of dam-break floods lacked detailed terrain modeling for complex underlying surface in urban regions. This paper presents a fine terrain modeling method based on TIN and NURBS. The method can be combined with an equivalent roughness method to distinguish the influences of flow resistance in different underlying surface conditions, so that it provides detailed underlying surface information for simulations of dam-break flood routing. To simulate the flood routing, a modified RNG k-ε model coupled with the VOF method was adopted and its accuracy was verified by model validation. We simulated dam-break flood cases for an urban reservoir with complex downstream inundation areas and analyzed the hydrological information including flood routing process, flow rate and water depth. The results show that the terrain modeling method reduces data storage and has good accuracy, and that the dam-break flood model simulates flood routing satisfactorily, thus reflecting the complex flow patterns and the details of the flows.