Scour hole development around piles - in the perspectives of hydrodynamics

Abstract

Scouring is a phenomenon that fluid brings sediment away at the bottom of the structure It is an important issue in subsea and marine engineering it may affect the stability of offshore structure The paper presents the numerical modelling of current induce scour around monopile and piles group in a side by side arrangement using the computational fluid dynamic software Flow-3D The software solves Navior-Stoke equation RNG model and k-ε model are test in order to choose a better turbulent model to simulate the initial progress of scour A numerical water tank with chosen sediment is established for a simulation The geometry and development process of scour hole were verified with the model test in Chen et al (2019) Vortex and shear stress are two variables of scour hole development In order to determine the influence of each variable on scouring shear stress and vortex are separate studied in different position The result using 2cm uniform grid indicate vorticity is a reason induce scour around cylinder(s) but the Reynolds stress is unable to observed in such grid size The mechanism of vorticity in different direction are also studied for a deeper understanding for local scour The integration of vortex and shear stress effect will cause the scour hole locates at downstream of piles The reason of scour hole geometry difference between gape ratios are caused by the vortex concentration after piles the narrower gape will induce a stronger vortex group after pile will form a deeper but narrower scour hole after piles group with a wider mound out of the scour hole

Date of Award	2020
Original language	English
Supervisor	Ray-Yeng Yang (Supervisor)