Emergence of coherent flow structures over a gravel surface: A numerical experiment

Hardy, R.J.; Lane, S.N.; Ferguson, R.I.; Parsons, D.R.

Abstract

Gravel bed rivers have complex, porous, and irregular surfaces, characterized by a range of morphological forms. These topographical structures determine the flow structures that develop over the river bed, primarily by the shedding of vortices in the downstream wake of protruding clasts. Previous research into these flow structures has come from experimental studies, which have used either flow visualization or single-point measurements techniques. Here we present a numerical experiment where large-eddy simulation (LES) is used to study the generation, evolution, and destruction of these flow structures over a naturally water worked gravel surface. The numerical simulations reported in this paper show that there are two distinct scales of boundary influence upon the shallow flow and emphasize that the measured flow variability at any one point in a natural river will contain both locally derived and upstream-inherited flow structures, according to the range of scales of bed topography present.

Citation

Hardy, R., Lane, S., Ferguson, R., & Parsons, D. (2007). Emergence of coherent flow structures over a gravel surface: A numerical experiment. Water Resources Research, 43(3), Article W03422. https://doi.org/10.1029/2006wr004936

• Journal Article Type: Article
• Publication Date: Mar 16, 2007
• Deposit Date: Oct 6, 2008
• Publicly Available Date: Mar 25, 2010
• Journal: Water Resources Research
• Print ISSN: 0043-1397
• Publisher: Wiley
• Peer Reviewed: Peer Reviewed
• Volume: 43
• Issue: 3
• Article Number: W03422
• DOI: https://doi.org/10.1029/2006wr004936
• Keywords: Coherent flow structures, Gravel bed rivers.