Effects of droplet shape on impact force of low-speed droplets colliding with solid surface

Experimental studies of low-speed droplets colliding with a flat solid surface are performed to record the impact force and deformation by using a highly sensitive piezoelectric transducer and a high-speed camera. The experimental data are used to verify the accuracy of a 3D numerical model via the smoothed particle hydrodynamics method, and the numerical method is used to explore the effects of the droplet morphology on the collision force. As the horizontal–vertical ratio of the droplets increases, the peak impact force increases by a power function trend and the time to reach the collision force peak decreases. The relationship between the equivalent volume of a spherical droplet and the volume of an ellipsoid droplet with different horizontal–vertical ratios under the same peak impact force is obtained. Self-similar theory is also suitable for droplets with ellipsoid shape. Finally, the stresses inside the material after large-sized spherical and small-sized oblate droplets hit the wall surface are compared. Results indicate that the curvature radius of droplets is a key factor that affects initial impact force and material erosion. Graphical abstract:

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