A Large-Eddy Simulation (LES) model is used to study flow dynamics of a flash flood event in a dry-bed, desert wash, the so-called Tex Wash, near the Tex Wash Bridge on Interstate 10 in the Mojave Desert of California. The evolving free surface of the flash flood is tracked using the level-set method. A bed morphodynamics module is coupled to the hydrodynamics model to calculate the erosion and bed evolution of the mobile bed of the wash under flash flood conditions. Flash floods in a desert wash can be characterized with a number of salient features such as the (1) existence of both the dry- and wet-cells on the bed surface of the wash that correspond to the air and water phases, respectively; (2) presence of various flow regimes, critical, sub-critical, and super-critical in the flow domain; and (3) occurrence of a highly transient and complicated flow field and, subsequently, sediment dynamics throughout the wash. A numerical modeling effort is presented to study a recorded flash flood and the corresponding scour processes in the Tex Wash. The flood event occurred in 2015 and lead to the collapse of the Tex Wash Bridge. The of the current study is to gain insight into the flood flow and sediment transport mechanisms, which resulted in the collapse of the bridge. To that end, a study area, which includes a 0.65 $\text{km}$-long reach of Tex Wash at its intersection with the Tex-Wash Bridge, was selected. The bathymetry of the wash was obtained using light-detection-and-ranging (LiDAR) technology and used to construct the computational domain of the wash and bridge foundations. The transient flow of the flash flood, in both air and water phases, and the evolving morphology of the wash are numerically simulated. The site-specific numerical simulation revealed the formation of deep scour regions adjacent to the right abutment of the upstream bridge, where significant erosion caused the collapse of the bridge. Moreover, the results show that most of the scour processes take place during the steady phase of the flash flood when the desert stream is filled with water. However, the transient phase of the flash flood is rather short and contributes to a very limited amount of erosion within the stream.

大涡模拟（LES）模型用于研究加州莫哈韦沙漠10号州际公路Tex洗涤桥附近的沙漠干燥床，所谓的Tex Wash中的山洪暴发事件的流动动力学。 。使用水平集方法跟踪山洪的不断演变的自由表面。床形态动力学模块与流体动力学模型耦合，以计算在暴洪条件下洗涤液移动床的侵蚀和床演化。荒漠冲刷中的山洪可具有许多明显的特征，例如：（1）冲刷床层上同时存在干细胞和湿细胞，分别对应于空气和水相。（2）流域中存在各种临界，次临界和超临界流态；（3）发生高度瞬态和复杂的流场，随后在整个洗涤过程中出现沉积物动力学。提出了数值模拟方法，以研究记录的山洪暴发和特克斯洗车场的冲刷过程，洪水事件发生在2015年，导致特克斯洗车桥倒塌。本研究的目的是深入了解洪水和泥沙输送机制，从而导致桥梁倒塌。为此，研究区域包括0.65 本研究的目的是深入了解洪水和泥沙输送机制，从而导致桥梁倒塌。为此，研究区域包括0.65 本研究的目的是深入了解洪水和泥沙输送机制，从而导致桥梁倒塌。为此，研究区域包括0.65$\text{公里}$选择了Tex Wash在与Tex-Wash Bridge交汇处的较长距离。使用光检测测距（LiDAR）技术获得洗涤物的水深，并用于构建洗涤物和桥梁基础的计算域。数值模拟了洪水泛滥在空气和水相中的瞬态流动以及洗液的演变形态。特定地点的数值模拟显示，靠近上游桥梁右基台的深冲区域的形成，在那里严重的侵蚀导致桥梁倒塌。而且，结果表明，大多数冲刷过程发生在山洪充满水的山洪暴发的稳定阶段。然而，