This paper describes an application of Large Eddy Simulation methods to
the flow in a laboratory-style confluence of parallel channels of
unequal depths (Reynolds No. approximate to 13,500), and a natural
river channel confluence that also exhibits pronounced bed discordance
(Reynolds No approximate to 100,000) The aim is to investigate the
formation of periodic flow features inherent in the flow dynamics in
river confluences. The laboratory-style confluence predictions are
compared with experimental data, and suggest that the simulation was
capable of capturing some of the key flow periodicities. The model
provides detailed flow and mixing data which help inform understanding
of the production and evolution of large scale turbulence features in
confluences.