The impact of the instrument in velocity measurements in an open channel with a porous bed

Abstract

In this study, the impact of the type of instrument used [hot-film anemometry and particle image velocimetry (PIV)] in velocity measurements in open channels with a porous bed is investigated. Individual experiments using both the hot-film anemometry and PIV methods were conducted. Initially, the experiments were performed with the hot-film anemometry method and then with the PIV method in open channels with a porous bed under the same conditions. To simulate the porous bed, porous filters, flexible vegetation, gravel beds, and rod bundles with the same porous thickness and the same porosity were used. The velocity distribution of the flow above the porous bed at different total water heights and the same channel slope was evaluated. The results showed that different instruments influence the velocity distribution of the flow, especially in the case of rod bundles. The results in the other cases (porous filters, flexible vegetation, and gravel bed) showed good agreement between the two methods regarding the velocity distribution. © 2017 by Begell House, Inc.