Author(s): F. De Serio; M. Ben Meftah; D. Malcangio; M. Mossa

Linked Author(s): Daniela Malcangio, Michele Mossa, Francesca De Serio

Keywords: Vegetated flow; Coherent vortices; Emergent vegetation; Vorticity; Suspended sediment transport

Abstract: Vortex structures produced by vegetation in a cross-flow strongly affect the transport of suspended sediment as well as the spreading of tracers. The present study aims to identify vortical coherent structures, based on experimental data. It is well established the interaction between vegetation and riverine or coastal flows, which plays a key role in many ecological functions and in flow-mass transport. The growth of the vegetated patches along with aquatic environments are influenced by the flow. Conversely, advection and turbulent mixing caused by vegetation alter flow by affecting flow resistance, sediment transport, water quality. Predicting dispersion processes in a vegetated current, which in turn affect sediment or tracers transport, requires thorough knowledge of the formation and spreading of some significant vorticity and turbulence that reorganizes in the shape of large-scale or coherent vortices. Generated by shear regions, they are recognized as organized vortical motions that significantly contribute to fluid entrainment, mass transport, momentum and heat mixing and advection. The flow-turbulence production within an array of emergent vegetation is dominated by the stem wakes rather than by the bed shear, as in open-channel flows. The aim of the present study is to assess the interaction of wakes and the location of coherent vortices due to the presence of neighbouring cylinders. The turbulent length scales governing the process are also evaluated.

DOI: https://doi.org/10.3850/978-981-11-2731-1_139-cd

Year: 2018