Interaction between the free surface and the vortical structures developed in a turbulent flow around a cylinder

The study and modeling of flow configuration around a cylinder is a benchmark CFD problem in fluid mechanics; the applications are multiple, from micro-fluidics to hydrology, from fluid-structure interaction to geophysics. The present paper is concerned with a particular motion related to this topic: the interaction between the free surface and the immersed cylinder in an open channel turbulent flow. The study is focused to the investigations of the vortical structures developed around the cylinder and their dependence on the distance from the free surface. Numerical simulations in 2D configurations are performed with VOF code and k-ε turbulent models. The calculations of the free surface and the direct flow visualizations disclose a good correlation. The results emphasis the major influence on the flow dynamics of the vorticity transport from the free surface to the cylinder. The locations of the critical points on the immersed surface are determined and the flow rate distribution around cylinder is computed.