Experimental comparison through LDA between currents with submerged vegetation

In this paper, the results of an experimental research concerning the comparison of two water currents flowing in the same rectangular channel over the same vegetated bed (an almost rigid submerged dense grass carpet), but with different deepness, are accurately described. In particular, the experimental plant is a rectangular channel, with variable slope, fed by a tank through a sluice gate, and ending through a weir. The two currents, generated from two different openings of the sluice gate, are characterized by the same equilibrium boundary layer developing at the inlet. Through an LDA system, the local mean velocity distributions of each current are obtained, and their comparison in dimensional and non-dimensional shape is described. The aim of the research is to apply to both currents a particular methodology of non dimensional representation of the velocity distributions that is characteristic of boundary layer streams but that has been in a previous paper already applied to a permanent current. The possible superposition of the velocity distributions of both the investigated currents would lead to the conclusion of the effectiveness of this methodology to represent all types of flow. The final results are that the two currents, in the suitable non dimensional shape, in spite of their different deepness, appear to behave in a practically identical way, so confirming the effectiveness of the proposed methodology of representation.