On the convective-absolute nature of river bedform instabilities

Riccardo Vesipa (1) , Carlo Camporeale (1) , Luca Ridolfi (1) , Jean Marc Chomaz (2)

1 Department of environmental, land and infrastructure engineering
2 LadHyX - Laboratoire d'hydrodynamique

River dunes and antidunes are induced by the morphological instability of stream-sediment boundary. Such bedforms raise a number of subtle theoretical questions and are crucial for many engineering and environmental problems. Despite their importance, the absolute/convective nature of the instability has never been addressed. The present work fills this gap as we demonstrate, by the cusp map method, that dune instability is convective for all values of the physical control parameters, while the antidune instability exhibits both behaviors. These theoretical predictions explain some previous experimental and numerical observations and are important to correctly plan flume experiments, numerical simulations, paleo-hydraulic reconstructions, and river works.

Domains: Fluid mechanics [physics.class-ph]

Riccardo Vesipa, Carlo Camporeale, Luca Ridolfi, Jean Marc Chomaz. On the convective-absolute nature of river bedform instabilities. Physics of Fluids, 2014, 26 (12), pp.124104. ⟨10.1063/1.4902901⟩. ⟨hal-01114977⟩