Author(s): S. I. Hayashi; T. Ohmoto
Linked Author(s):
Keywords: DNS; Coherent structures; Sand ribbon; Cellular secondary currents; Open channel turbulence
Abstract: Fully developed three-dimensional turbulent flow over sand ribbons in an open-channel is computed to investigate the coherent structure of streamwise vortices by Direct Numerical Simulation (DNS) using a regular grid under a generalized curvilinear coordinate system. Coherent structures are educed from the simulated instantaneous flow field using conditional sampling techniques developed by Hunt et al, Jeong & Hussain that extracts the entire extent of dominant vortical structures. The results showed that stable secondary currents and turbulent characteristics were reasonably reproduced, highly elongated quasi-streamwise vortices were identified and the streamwise vortices of alternating sign were recognized to stagger over the sand ridge.
Year: 2003