Flow Structure within a Vegetation Patch in an Experimental Flume

Submerged vegetation patch plays a significant role in flow structures in river engineering. Although the existing theories of mixing layer can be applied to investigate the interaction of vegetation patch and flow, the effect of developing flow over small patches has not been yet considered in the literature. This experimental study applies the mixing -layer theory over artificial vegetation patch for two flow discharges 21 and 29 l/s. The results reveal that the mixing-layer thickness over the vegetation patch follows a logarithmic trend for developing and fully developed flow regions and the diffusion coefficient is less than the reported values in literature due to the limitation of vertical development of the mixing layer width by the bed and small canopy height. Also, there is a reasonable agreement between the measured values with the estimated ones by the mixing- layer over vegetation patch. The convex Reynolds stress distribution calls for more consideration in estimation roughness coefficient and sediment transport over vegetation patch under developing flow.