Effective simulation of flow in a moderately curved bend with a single short branch to support the design optimization of river-branch-plant configurations

The initial space settings of suitable environments for plants strongly affect the mutual feedback evolution of the river landscape and terrestrial plants. Thus, based on the morphological characteristics of newly-defined systematic out-branching channels in nature, this study performs an effective simulation of the flow of a designed moderately curved bend with a single short branch. The practice-based channel curvatures and branch on-off conditions are controlled in ANSYS FLUENT. The results show that: (1) the core zone of the depth-averaged primary velocity excess is approximately inversely equivalent to the channel migration potential; (2) the existence of the branch can strongly promote the formation of a new core vorticity zone and the conflicting development of the inner-negative and outer-positive vorticity zone after the bifurcation site at the cross-sections; (3) the free-flowing branch can greatly diminish the downstream helical flow strength; overall, the variation tendency of the ratio of helical flow strength to discharge squared is immune to the small range of change in stable inflow; and (4) the downstream channel is a strongly erosive region with the branch outlet closed, judging by the shear stress distribution; otherwise, it is a deposition region. The findings lay the groundwork for harmonious optimization of branch and plant configurations in river-bend systems.