The hydrodynamics in a straight open channel with a multiple-embayment groyne field was investigated using the detached-eddy simulation (DES). A series of short groynes were included on a 1:3 side slope of the channel. This work focuses on the turbulent coherent structures around groynes on an uneven bottom. Flows around groyne fields are characterized by massive separation and highly unsteady vortices. DES can capture a wide spectrum of eddies at a lower computational cost than the large eddy simulation (LES) or direct numerical simulation (DNS). In the present work, a zonal DES model (ZDES) was used to simulate the flow around groynes. The ZDES model is a modified version of the DES designed to overcome the model-stress depletion (MSD) of the RANS/LES hybrid model. The vortex system consists of the horseshoe vortex (HV) formed at the base of the obstructions, the necklace vortex (NV) that wrapped the groyne tips near the free surface, and the shedding vortex (SV) underneath the free surface. The effects of the incident flow and local topography on the vortex evolution were investigated by analyzing the mean flow structures and the instantaneous turbulent flow fields. Some important vortices cannot be captured because of the averaging process, while some flow structures cannot be observed in the instantaneous flow. The mean flow is only a reflection of the averaging process when complex vortices are present.

中文翻译：

---

梯形明渠中堤坝周围湍流相干结构的分离涡模拟

使用分离涡模拟（DES），研究了具有多嵌入地漏场的直开放通道内的流体动力学。在通道的1：3侧坡上包括一系列短的防波堤。这项工作的重点是在不平坦的底部上，围绕着防波堤的湍流相干结构。河田周围的水流以大量分离和高度不稳定的涡旋为特征。与大型涡流模拟（LES）或直接数值模拟（DNS）相比，DES可以以较低的计算成本捕获各种涡流。在当前的工作中，使用了区域DES模型（ZDES）来模拟绕丁坝的流动。ZDES模型是DES的修改版本，旨在克服RANS / LES混合模型的模型应力耗竭（MSD）。涡流系统由在障碍物底部形成的马蹄形涡流（HV），在自由表面附近包裹着防波堤尖端的项链涡流（NV）和自由表面下方的脱落涡流（SV）组成。通过分析平均流结构和瞬时湍流场，研究了入射流和局部地形对涡旋演化的影响。由于平均过程，一些重要的涡流无法捕获，而在瞬时流中则无法观察到某些流动结构。当存在复杂的涡流时，平均流量仅是平均过程的反映。通过分析平均流结构和瞬时湍流场，研究了入射流和局部地形对涡旋演化的影响。由于平均过程，一些重要的涡流无法捕获，而在瞬时流中则无法观察到某些流动结构。当存在复杂的涡流时，平均流量仅是平均过程的反映。通过分析平均流结构和瞬时湍流场，研究了入射流和局部地形对涡旋演化的影响。由于平均过程，一些重要的涡流无法捕获，而在瞬时流中则无法观察到某些流动结构。当存在复杂的涡旋时，平均流量仅是平均过程的反映。