Author(s): Huan Tao Goh; Akihiko Nakayama; Zafarullah Nizamani And Atsuhiro Yorozuya
Linked Author(s): Akihiko Nakayama
Keywords: River bend ADCP survey LES simulation Sediment deposition Scouring
Abstract: In order to understand the flow and the sediment transport mechanisms in the meandering lower reach of Perak River in Malaysia, an Acoustic Doppler Current Profiler (ADCP) survey and a Large Eddy Simulation (LES) simulation have been conducted along with the sediment sample analyses. The part of the river is under tidal effects and flow rates vary from about 1200m3/s towards the sea and 300 m3/s in the upstream direction depending on the tidal stage cycle. In order to know the dominant flow characteristics in the present study, the survey and the simulation were conducted during the tidal cycle with the seaward flow. The flow upstream of the study reach is relatively straight and smooth with little lateral mixing. Then flow goes through series of bends that induce the erosion and the deposition as the flow winds around the curves and the river width changes. The three-dimensional flow field measured by the ADCP traverses indicate the alternating slow and fast flow areas. The LES simulation is done for a short period of seaward flow period that gives the detailed secondary flows and the bed shear stress distribution. Although the complex flow pattern obtained by the ADCP survey and the LES simulation do not agree in the detail, the sediment survey and the simulated bed shear stress agree with the observation of the bed changes.
Year: 2025