The impact and absorption of a droplet onto a paper substrate can be studied with computational fluid dynamics software. In the FLOW-3D animation shown below, the drop is 40 microns in diameter, with an initial downward velocity of 300 cm/s. The substrate is paper and is 20 microns thick with a given porosity of 30%. The droplet surface is colored by pressure and fraction of fluid of the droplet is shown as it impacts the paper.
Fraction of fluid of the droplet is shown as it impacts the paper.