Author(s): Sina Wunder; Boris Lehmann; Franz Nestmann
Linked Author(s): Sina Wunder
Keywords: No Keywords
Abstract: This paper presents an experimental setup that enables the direct determination of the vegetal drag coefficient cd based on the turbulence-theoretical approaches of Lindner and Pasche. For this purpose the formula of drag force is applied. The development of the setup equipment, consisting of a framework simply supported at the channel walls, took place in a 20 m long, 1 m wide and 0.4 m high flume of the TheodorRehbock-Laboratory in Karlsruhe. The vegetal drag coefficient cd can be calculated by the measured drag force with known values of fluid density, flow velocity and projected vegetation area. Defining the results of the measured drag coefficient cd depending on the Reynolds number in a diagram allows the direct comparison to the analysis of Schlichting. The investigation revealed that the drag coefficient of flexible willow branches are approximately twice as the drag coefficient of stiff aluminium rods.
Year: 2009