Analysis of Vegetation Resistance Based on Two Typical distribution
types in Ecological channel
Abstract
This paper studied the potential mechanism of form drag from emergent
vegetation by the effective combination of experimental verification and
numerical simulation. The rigid cylindrical sticks arranged in the open
channel were used to simulate vegetation and experiments on flow
velocity distribution characteristics in open channel with different
vegetation density and vegetation arrangement forms were carried out.
Based on the new expression of hydraulic radius from the recent paper,
it indicates the form drag from vegetation is closely related with the
wake volume near the vegetation. The relationship between the wake
volume and form drag is proposed and verified by different experimental
conditions. Based on this relationship, the experimental results show
that the resistance form of vegetation in vegetated open channels can be
divided into: K-type and D-type based on different sticks arrangement
within one vegetation patch. The calculated values and measured values
achieve a good agreement under different experimental conditions.
Meanwhile, numerical simulation based on SAS turbulence model was
conducted and the simulation results also fit well with the experimental
values so more complex experimental conditions are simulated by
numerical simulation method. The results of this study will provide a
theoretical basis for the layout of vegetation in the ecological open
channel.