Author(s): Qiaochao Liu; Changrong Yao
Linked Author(s):
Keywords: Twin piles; Scour hole; k-ω model; Horseshoe vortices; Wake vortices; FTLE; Sediment transport
Abstract: Twin piles are commonly used in coastal structures and bridge piers. In present study, the flow field around five sets of series-arranged twin piles and seven sets of staggered twin piles on both flatbed surfaces and within a scour hole is numerically simulated using the k-ω model. Horseshoe vortices (HVs) and wake vortices (WVs) are identified using the q-criterion method. For configurations with small spacing, the HVs from downstream cylinders are diminished by the WVs from upstream cylinders, with the WVs of the upstream cylinder reattaching to the downstream cylinder. Under the influence of the scour hole, the tails of the Wake Vortices (WVs) extend in the direction of the flow. The finite time Lyapunov exponent (FTLE) method and particle trajectory analysis are employed to study the transportation of suspended sediment. Once surface sediments around the piles become suspended due to scouring, they are drawn into the near wake area and temporarily trapped, a process that is intensified by the downstream cylinder. Furthermore, the scour hole also influences the drag force on the piles, with the distribution of drag force being analyzed as well.
Year: 2024