Author(s): Bernhard Vowinckel; Tobias Kempe; Jochen Fröhlich
Linked Author(s): Bernhard Vowinckel
Keywords: Direct numerical simulation; Immersed boundary method; Open-channel flow; Sediment transport; Moving-frame analysis
Abstract: The paper presents highly resolved Direct Numerical Simulations of bed-load transport in an open channel flow with low submergence. Thousands of mobile particles are transported over a rough bed consisting of immobile spherical particles of the same size in hexagonal ordering. The disperse phase is represented by an Immersed Boundary Method with each particle being resolved with 22 points per diameter. The large computational domain allows for the formation of bed-load features with high fidelity. In particular, the characteristic flow fields reflecting the interaction between the fluid and the collective motion of particle clusters propagating with a considerable velocity in streamwise direction are addressed. For this purpose, a moving frame analysis was carried out detecting and following the center of mass of a particle cluster in order to obtain a transformed coordinate system with conditions as stationary as possible. This measure allows a detailed and statistically well-averaged analysis of the collective behavior of the sediment.
Year: 2015