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Rivulet dynamics is involved in different scientific problems and industrial applications from production of microchips, to rain flow on structural systems such as wind turbine blades and aircraft wings. In the latter case for example, rivulet flow leads to accumulation of ice on airfoil surface that may affect the aircraft performance. Hence, understanding the dynamics of rivulets is important in solving various scientific problems. In this paper the results of a numerical simulation based on smoothed particle hydrodynamic (SPH) method will be reported on dynamics of rivulets under the effect of various air shear speeds and different surface morphologies. The simulation results will be compared and validated with experiments to shed more lights in understanding the mechanism of shear driven rivulet flow on solid substrates.

Experimental study is performed to analyze the shedding behavior of droplets with different shear flow speeds typical of those in the flight conditions. Droplet shedding phenomena has significant effect on ice accumulation on critical components such as airfoil and nacelle. In order to mimic this scenario experimental set up is designed to generate shear flow as high as 90m/s. The high shear effect is combined to the surface wettability impact by using hydrophilic and superhydrophobic surfaces. It is shown that the wetting length of the droplet on hydrophilic surface increases by shear speed while on the superhydrophobic surface a drastic reduction on wetting length is detected. Furthermore, it is observed that the droplet is detached from the superhydrophobic surface with moderate shear speeds.

One of the relevant applications of this study is related to designing anti-icing surfaces. Supercooled water droplet impact at high Weber number on a wing of airplane is one of the main concerns in aircraft ice accumulation. In order to address this issue, an experimental setup which generates co-flow is designed to mimic the real scenario of droplet impact in practical icing condition. This process is observed using a high-speed camera to capture the correct moment of sliding at 10000 frames per second and 120000 1/s shutter speed. Different air stream velocities are generated by a convergent nozzle with a maximum Mach number of 0.1. Two different cases are considered. First, droplet impact in still air with an impact velocity of 2 m/s is performed as the base case. Then droplet impact accompanied with 10, 18 and 20 m/s air stream velocities having the same impact velocity are conducted. Droplet impact velocity will change either by air flow or gravity.