Experimental, Numerical, and Analytical Study of a Droplet Impact on Parallel Fibers

The statics of droplet hanging from the parallel fibers and the dynamics of droplet impact on the parallel fibers are investigated using high-speed imaging and volume of fluid numerical simulation. Experimental results show for the parallel fibers, the maximum volume of the droplet, which is able to hang statically from the fibers is measured to vary between 1.85 to 1.9 times of the one measured for a single fiber. The dynamics of droplet impact have been studied by varying the radius of the impacting droplet, the fibers radius, and the distance between the fibers. The threshold velocity of droplets by fibers has been obtained both experimentally and numerically with the fluid volume method. The results show that by increasing the impacting droplet radius and decreasing the fibers radius, the threshold velocity of droplet capture decreases. The maximum threshold velocity of droplet capture with parallel fibers varies in the range of 1.5 to 1.8 times of the threshold velocity of capture with a single fiber. The maximum threshold capture velocity of droplets occurs where the distance between fibers is in the range of 0.35 to 0.5 times of impacting droplet diameter. The threshold capture velocity on parallel fibers is also obtained analytically, using the energy balance method. The results of the analytical solution are in a fair agreement with experimental data and numerical simulation results.