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Drag Coefficient of Rigid Vegetation in Subcritical Open Channel Flow

Author(s): Xiao-Guang Liu; Yu-Hong Zeng

Linked Author(s): Yuhong Zeng

Keywords: Drag coefficient; Subcritical flow; Rigid vegetation

Abstract: Vegetation in fluvial systems plays an important role in environmental and ecological aspects. Vegetation can cause energy dissipation by drag force due to the interaction between vegetation and flow in which the dimensionless drag coefficient (C d) is of great importance for understanding and predicting the drag force. Currently C d was determined through model experiments and mass literature about subcritical open channel flow with rigid vegetation can be obtained. A data processing method was introduced to seek an empirical prediction for C d. Firstly, the influencing factors of C d was determined by dimensional analysis method. Then based on the collected data, we used multi-parameter regression analysis to obtain the empirical expression of C d by those dimensionless influencing factors. It is interesting to find that drag coefficients for sub-and supercritical flows have opposite trends with varied vegetation density, and C d remains almost constant with high Froude number for subcritical flow, or the Froude number has little impact on C d; while for subcritical flow with low Froude number, the effect of Froude number cannot be ignored.


Year: 2016

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