| Summary: | The vegetation density <i>λ</i> affects turbulent flow type in the submerged vegetated river. This laboratory study investigates different types of vegetated turbulent flow, especially the flow at 0.04 < <i>λ</i> < 0.1 and <i>λ</i> = 1.44 by setting the experimental <i>λ</i> within a large range. Vertical distributions of turbulent statistics (velocity, shear stress and skewness coefficients), turbulence kinetic generation rate and turbulence spectra in different <i>λ</i> conditions have been presented and compared. Results indicate that for flow at 0.04 < <i>λ</i> < 0.1, the profiles of turbulent statistics manifest characteristics that are similar to those of both the bed-shear flow and the free-shear flow, and the turbulence spectral curves are characterized with some slight humps within the low-frequency range. For <i>λ</i> = 1.44, the turbulent statistics above the vegetation top demonstrate the characteristics of boundary-shear flow. The spectral curves fluctuate intensely within the low-frequency range, and the spectra of low-frequency eddies above vegetation top are significantly larger than the values below. The change of turbulent flow type induced by an increase of <i>λ</i> would increase the maximum value of turbulence kinetic generation rate <i>G</i><sub>S</sub> and change the point where <i>G</i><sub>S</sub> is vertically maximum upwards to the vegetation top.
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