Tumbling of quasi-straight to slightly curved fibers in channel flow turbulence

In this study, we investigated the tumbling dynamics of quasi-straight to slightly curved fibers via ''adaptive filtering'' and we have been able to report a universal scaling for the tumbling rate of the fibers. Fibers used in this study are in order of (1-2) times of Kolmogorov length scale of the flow for the lowest Reynolds number examined. Results for the channel center, the most homogeneous part of the flow, are compared and benchmarked with previously reported tumbling rates for straight rods in Homogeneous Isotropic Turbulence (HIT). We addressed the hypothesis which relies on simplifying the dynamics of slightly curved fibers as straight fiber and show that this is possible only by using a correction factor which is defined based on an analytical model reported by Hinch & Leal (1979). By means of this correction factor, we show that the magnitude of the tumbling rate for quasi-inertialess fibers is independent of fibres asymmetry rate and location in channel height.