Author(s): Obaidullah Safie; Akihiro Tominaga
Linked Author(s): Akihiro Tominaga
Keywords: Permeable groyne; Riverbank protection; Spur dike; Turbulence characteristics; Velocity reduction
Abstract: Many pile-group groynes have been used along the Kiso and Yahagi Rivers in Japan for bank protection purposes. Obviously, the arrangement of piles in a group significantly affects downstream flow structure. However, these effects have not been sufficiently studied. In this study, flow structure and turbulence characteristics in a long downstream distance of different pile-groups were investigated. Two types of pile arrangement, namely in-line and staggered arrays, were considered. The main purpose of this study was to evaluate the performance of various pile-group groynes for velocity control along the bank. The results demonstrated significant effects of pile arrangement on both flow structure and turbulence characteristics. The staggered type caused a gradual deceleration of flow from the mainstream toward the bank, while the in-line type did not yield a smooth reduction of flow. In contrast with the in-line arrangement, the staggered type maintained the low-velocity field in a long downstream distance. Furthermore, the staggered type caused a drastic reduction in the turbulence around the structure when compared with the in-line type. Different flow structures and turbulence characteristics generated by various arrangements of piles were well simulated with a two-dimensional numerical model.
Year: 2020