The short course will discuss in depth the physics of shallow mixing layers and shallow mixing interfaces and of the related transport processes in both canonical configurations and in natural environments (river confluences) across a wide range of scales. The course will discuss how the structure and spatial development of the mixing interface are affected by density contrast between the incoming flows, channel bathymetry, confluence angle, bed roughness, etc. It will present the state of the art in terms of laboratory, field and numerical studies used to investigate the flow structure and dynamics of such flows. It will show the critical role played by large-scale turbulence in controlling mixing, sediment transport processes and spatial patterns of water quality and biodiversity. The course will emphasize a synergetic approach in which experimental and numerical techniques are jointly used to reveal new knowledge and explain phenomena observed at natural river confluences under a wide range of conditions and scales. A preliminary list of the main topics covered is given below. The course will also offer the participants the chance to directly interact and exchange research ideas with the lecturers.

The course is co-organized by the IIHR Fluvial Hydraulics Committee (Prof. George Constantinescu, Univ. Iowa, USA) and the IIHR Fluid Mechanics Committee (Prof. Vlad Nikora, Univ. Aberdeen, U.K.). The theoretical modeling and experimental studies module will be led by Dr. Sebastien Proust (INRAE, France). Prof. Carlo Gualtieri (Univ. Federico II Naples, Italy) will lead the module focusing on field studies of flow, mixing, sediment transport and ecological processes at river confluences. Prof. George Constantinescu will cover eddy-resolving numerical studies of confluent flows in idealized geometries and natural river confluences.

The course dates are August 31 and September 1, 2024. We anticipate about 6 hours of lecture per day with each module covered in about 4 lecture hours. There is no fee registration to attend the course provided the participant paid the conference registration fee. The participants will need to secure accommodations for the two extra days before the main conference activities start on September 2. Interested participants should contact via e-mail Prof. George Constantinescu ( and Prof. Iacopo Carnacina ( The email should include a one-page CV and a short paragraph explaining the interest of the participant in taking the short course. We encourage the participants to contact us early. Applications will be received until August 23, 2024. For any additional questions related to the course please contact Prof. George Constantinescu.

1) Theoretical and laboratory studies of shallow mixing layers
• Emergence and fate of the coherent structures in shallow mixing layers
• Shallow mixing layers over hydraulically smooth versus rough beds
• Shallow mixing layers in rectangular versus two-stage open channels
• Shallow mixing layers induced by a lateral change in hydraulic roughness
• Interplay between flow structures in shallow mixing layers

2) Field studies of river confluences
• A review of recent studies across different scales: Hydrodynamics, sediment transport, mixing and ecological issues
• The effect of density differences at large-size confluences
• Diffluence-confluence units
• Three case-case-studies of large-size confluences: Amazon, Yangtze, Yarlung Zangbo-Brahmaputra

3) Numerical simulations
• Shallow mixing layers and shallow mixing interfaces in constant depth, wide channels: Effects of velocity ratio, confluence angle and channel curvature
• Flow and mixing processes at natural river confluences with a concordant bed
• Shallow mixing interfaces with density contrast between the incoming streams in constant depth, wide channels
• Density contrast effects on flow and mixing at natural river confluences with a concordant bed
• Flow structure and mixing processes at natural river confluences with a discordant bed

Relatori ad invito: Dr. Sebastien Proust (INRAE, France)
Prof. Carlo Gualtieri (Univ. Federico II Naples, Italy)
Prof. George Constantinescu (Univ. Iowa, USA)

Termine per la registrazione:

Prof. George Constantinescu (
Prof. Iacopo Carnacina (

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