Logo image
Back
A Numerical Study of the Effects of Density Contrast on Flow, Turbulence, and Mixing at the Negro/Solimoes Confluence, Brazil
Journal article   Open access   Peer reviewed

A Numerical Study of the Effects of Density Contrast on Flow, Turbulence, and Mixing at the Negro/Solimoes Confluence, Brazil

C. Jiang, M. Koken, G. Constantinescu and C. Gualtieri
Water resources research, Vol.62(5), e2025WR041934
05/01/2026
DOI: 10.1029/2025WR041934
Appears in  UI Libraries Support Open Access
url
https://doi.org/10.1029/2025WR041934View
Published (Version of record) Open Access

Abstract

Eddy-resolving numerical simulations are conducted to investigate the effects of density contrast between the confluent flows on hydrodynamics, coherent structures and mixing downstream of the confluence between the Negro and Solim & otilde;es Rivers, Brazil, which is characterized by both a large discharge (>100,000 m(3)/s) and a large aspect-ratio (W/D > 100). The base case corresponds to real high-flow conditions observed at the confluence for which the density of the Negro River was smaller than that of the Solim & otilde;es River and the ratio between the discharges in the Negro and Solim & otilde;es rivers was QR = Q(1)/Q(2) = 0.32. To be able to understand and isolate density contrast effects, numerical experiments are also conducted assuming negligible density effects between the incoming flows (i.e., with Richardson number Ri = 0) and with the densities reversed in the incoming streams. Despite the small density difference and very large discharges, a well-defined near-bed intrusion of heavier colder fluid develops in the Ri > 0 simulations and strongly affects the tilting of the mixing interface (MI) compared to the Ri = 0 case where despite the absence of streamwise-oriented vortical cells, the MI is strongly tilted toward the Negro River side of the main confluence channel. Moreover, the presence/absence of density contrast between the incoming streams affects the position, size and sense of rotation of the main helical cells of crossflow motions and the coherence of the vertical MI vortices.
 river confluences vortices mixing layers turbulent mixing stratification effects eddy resolving model UIOWA OA Agreement

Details

Metrics

1 Record Views
Logo image