In this paper, we report the turbulent flow structures and the scour geometry around two piers with different diameters. An experiment was conducted on a non-uniform sand bed with two types of tandem arrangements, namely, pier (T1) with a 75 mm front and 90 mm rear, and pier (T2) with a 90 mm front and 75 mm rear, with and without-seepage flows, respectively. A strong wake region was observed behind the piers, but the vortex strength diminished with downward seepage. Streamwise velocity was found to be maximum near the bed downstream of the piers and at the edge of the scour hole upstream of the piers. Quadrant analysis was used to recognize the susceptible region for sediment entrainment and deposition. Upstream of the piers near the bed, the moments, turbulent kinetic energy (TKE), and TKE fluxes were found to decrease with downward seepage, in contrast to those in a plane mobile bed without piers. The reduction percentages of scour depth at the rear pier compared with the front one were approximately 40% for T1 and 60% for T2. Downward seepage also resulted in restrained growth of scouring with time.

在本文中，我们报告了两个直径不同的墩周围的湍流结构和冲刷几何形状。在具有两种串联布置的非均匀砂床上进行了实验，即前75毫米，后90毫米的墩（T1）和前90毫米，后75毫米的墩（T2），其中和无渗流。在码头后面观察到一个强大的尾流区，但涡流强度随着向下的渗漏而减弱。发现在码头下游的床附近和码头上游的冲刷孔的边缘，水流速度最大。象限分析用于识别泥沙夹带和沉积的敏感区域。在靠近床层的桥墩的上游，弯矩，湍动能（TKE）和TKE通量随向下渗流而减小，与那些没有码头的平面移动床相反。与第一个墩相比，后墩的冲刷深度减少百分比约为T1 40％和T2 60％。向下的渗漏也导致了随着时间的推移冲刷的增长受到限制。