Large Eddy Simulation of Oscillatory Flow, Sediment Transport and Morphology Evolution over Ripples based on the Immersed Boundary Method

摘要

In the present study, a three-dimensional numerical model has been developed, in order to study the sediment dynamics that occur in oscillatory flow over ripples. A morphology module has also been developed in order to perform two-dimensional simulations of the bed form evolution under hydrodynamic forcing. Results are presented for oscillatory flow over fixed ripples, at Reynolds number 23,163. The suspended sediment rise is highly correlated to the elevation of the flow vortices after their generation due to flow separation at the lee side of the ripples. The influence of the ripple height on the behaviour of suspended sediment is also significant. Concerning the evolution of the bed form, results of ripple creation, growth, merging, and annihilation are presented.