Author(s): Jorge D. Abad; Javier Ancalle; Gustavo C. Aglia; And Marcelo H. Garcia
Linked Author(s): Jorge D. Abad
Keywords: Open channel (cid: 13) ow; Meandering streams; Secondary circulation; Turbulence; Laboratory experiments; Flow measurements 1
Abstract: Meandering rivers exhibit complex planform patterns. The main ob jective of this study is to observe the in (cid: 13) uence of bend orientation on the hydrodynamics and morphodynamics of high-amplitude meandering channels. In this paper, only hydrodynamics results are presented by experimental and numerical approaches. In the experimental part, mean and turbulent (cid: 13) ow structures have been investigated for the case of periodic assymetric meandering channel. The channel planform con (cid: 12) guration of the designed (cid: 13) ume retains high-order harmonic modes, thus, cases where meander bends are oriented upstream- and downstream-valley can be studied. In order to describe the e (cid: 11) ects of bend orientation on the channel hydrodynamics, a (cid: 13) at smooth bed (no sediment) condition has been considered to purely describe the e (cid: 11) ects of bend orientation on the hydrodynamics of the meandering channel. In the numerical part, an in-house Finite Element (FE) model is applied to solve the hydrodynamics of the Kinoshita meandering channel. The hydrodynamic model solves the 3D Reynolds Averaged Navier-Stokes (RANS) equation and the k (cid: 0) (cid: 15) equations for turbulence. The model uses a Eulerian Level Set Method to capture the free surface (gas-liquid interface). The model is validated comparing our measurements against numerical results, thus, the model can be used to simulate hydraulic conditions where measurements could not be taken due to shallowness of the (cid: 13) ow, due to proximity of walls, and due to operational experimental conditions. Both experimental and numerical results show that at the bend apex, the core of maximum velocity is found near the inner bank (for both bend orientations). Also, at the bend apex, the results show that when bends are oriented upstream-valley, the secondary (cid: 13) ow is not as developed as in the case where bends are oriented downstream-valley.
Year: 2007