Laboratory study of density-driven streamwise orientated vortices at a symmetric confluence

Résumé fourni par la source

Recent studies have shown small density gradients between a confluence’s tributaries (i.e. ∆ ρ = 0.5 kg/m 3 ) can greatly affect its secondary flow structure. In particular, streamwise orientated vortices (SOVs) at the Coaticook-Massawippi confluence (Quebec, Canada) were purported to be previously undocumented confined density-driven gravity currents. This flow structure develops when a near-bed front of the dense tributary and a near-surface front of the light tributary are confined by the tributaries that oppose them. However, neither the confined gravity current mechanism nor the resulting density SOVs have empirical support. A laboratory model of a symmetric confluence with a tunable density gradient was constructed for this purpose and persistent clockwise rotating density SOVs were confirmed in its mixing interface. The empirical density SOVs share many similarities to those observed and modeled at the Coaticook- Massawippi confluence, suggesting they are a universal and scale-independent secondary flow structure when certain hydrodynamic and density conditions align.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.