Characterization of vortical structures and loads based on time-resolved PIV for asymmetric hovering flapping flight

Numerical investigation of three-dimensional asymmetric hovering flapping flight

“…They showed that a peculiar feature of asymmetric hovering was the absence of significant wake capture mechanism during downstroke, due to the relatively weak upstroke angle of attack and the absence of significant leading edge vortices (LEV). This was in line with previous experimental results of 8 obtained using time-resolved particle image velocimetry (PIV) and non-intrusive load measurements.…”

“…Yet, it is observed that the potential increase in CV is larger for low values of α 1 while the potential increase in CV / CP is larger for high values of α 1 . At this point, present results thus support previous observations on two-dimensional configurations where asymmetry was found to promote aerodynamic performance [6][7][8] In order to provide further insight into the cause for increases in CV and CV / CP with asymmetry we first display CV and CV / CP as a function of β in figure 5. β is an indirect measure of the degree of asymmetry (i.e.…”

On the non-intrusive evaluation of fluid forces with the momentum equation approach

“…The instruments and procedures used in the experiments have been described elsewhere (Jardin et al 2009). A transparent NACA0012 profile of chord 60 mm and span 50 cm, placed between two end plates in a 1 × 1 × 2 m 3 water tank, is translated by means of a servo-controlled motor.…”

How shape and flapping rate affect the distribution of fluid forces on flexible hydrofoils

“…The research field making use of PIV/PTV-based pressure evaluation covers a large collection of hydrodynamics problems, from micro-channel junction flow and turbine blades to animal locomotion (Gresho & Sani 1987;Baur & Köngeter 1999;Gurka et al 1999;Jakobsen, Dewhirst & Greated 1999;Fujisawa et al 2006;Liu & Katz 2006;van Oudheusden, Scarano & Casimiri 2006;Murai et al 2007;van Oudheusden et al 2007;van Oudheusden 2008;Windsor 2008;Jardin, David & Farcy 2009;Lorenzoni et al 2009;Khodarahmi et al 2010;de Kat & van Oudheusden 2012;Ragni, van Oudheusden & Scarano 2012;de Kat & Ganapathisubramani 2013;van Oudheusden 2013;Panciroli & Porfiri 2013;Dabiri et al 2014;Joshi, Liu & Katz 2014;Tronchin, David & Farcy 2015;Lucas et al 2017;McClure & Yarusevych 2017;Mwaffo et al 2017). Accurate and non-invasive methods to measure the fluid forces directly on the surface of flapping fins are essential to investigate the mechanisms of underwater propulsion.…”