Parameterization of the modeling variables in velocity analytical solutions of open-channel flows with double-layered vegetation
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This paper presents a descriptive analysis of the double layer vegetation flow and the application of different empirical models for velocity distribution in vegetation flow. To establish the models, extensive experiments are carried out using plastic dowels of differential heights, configurations and densities. The previous models based on empiricism and momentum balance are applied here and found to work satisfactorily. However, it is found out that the boundary conditions play a significant role to capture inflection over vegetation level. Furthermore, the most important factor for capturing the inflection above zero plane displacement is to understand the intermediate boundary conditions and their superposition rather than extremum conditions. Therefore a new model for mixing length over the short vegetation height has been suggested. The results from the velocity distributions, turbulence intensity and vorticity of the experimental data are used to derive a new relationship for mixing length under certain assumptions. For establishing the proposed model other researchers’ data are considered and finally corroborated for the validation set, which suggests that the proposed model agrees reasonably well with the measured data.
KeywordsBoundary layer Vegetative flow Double-layered Mixing length Von-Karman street
The authors would like to thank the Nanjing Hydraulic Research Institute and their staff for their support, and also acknowledge the financial support by the Research Development Funding of XJTLU (RDF-15-01-10).
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