Author(s): C. W. Li; C. Zeng
Keywords: Open channel; Flow diversion; Vegetation; 3D flow model
Abstract: Flow diversion in channel junction is an important problem in drainage engineering. The growth of vegetation in channel system is environmental friendly but its effect on channel junction flow has not been investigated. In this work a 3D RANS (Reynolds Averaged Navier-Stokes equation) model is used to investigate the flow phenomena in vegetated channel junctions. Emphasis is on the determination of the effect of vegetation on flow division. The model is first validated by two limiting cases: flow in open channel junction without vegetation, and flow in a single open channel with vegetation. In application of the model to flow in vegetated channel junction, the results quantitatively predicts that the increase in vegetation density in the branch channel will direct more flow into the main channel. For the vegetation density greater than a certain value, further increase in its value only decreases slightly the amount of flow into the branch channel. The overall energy loss coefficient of the system however decreases with the increase in vegetation density. The findings lead to a novel way of controlling flow diversion using vegetation.