Abstract
Abstract
Highlights
A drop impacting a dry solid substrate will either spread tangentially to the surface without breaking or will splash, disintegrating into tiny droplets ejected radially outwards at velocities far larger than the impacting one (Yarin 2006; Josserand & Thoroddsen 2016)
These are, precisely, the most common conditions involving the impact of a drop against a solid found in both practical applications and in our daily life experience: think, for instance, of rain drops falling on the sidewalk, which clearly is a rough substrate like the vast majority of solids
In this contribution we report experimental results obtained when millimetric drops of water and ethanol of radii R fall over sandpapers with different values of the substrate roughness, ε
Summary
A drop impacting a dry solid substrate will either spread tangentially to the surface without breaking or will splash, disintegrating into tiny droplets ejected radially outwards at velocities far larger than the impacting one (Yarin 2006; Josserand & Thoroddsen 2016). It will be assumed that the drop falls over the solid perpendicularly because the effects associated with the impact direction (Bird, Tsai & Stone 2009; Almohammadi & Amirfazli 2017; Hao & Green 2017; Hao et al 2019) can be accounted for using the framework put forward in, for instance, Gordillo & Riboux (2019) and García-Geijo, Riboux & Gordillo (2020) As it was mentioned above, Mundo et al (1995) studied the case of drops impacting at normal atmospheric conditions on either smooth or rough dry surfaces and characterized the spreading–splashing transition through the so-called K parameter, or splashing parameter, which is nothing but a correlation involving the Reynolds and Ohnesorge numbers based on the liquid properties.
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