Absorption and Spreading of a Liquid Droplet Over a Thick Porous Substrate

Spreading over porous substrates occurs in several processes including printing, cleaning, coating, and manufacturing of ceramic structures. For small drops, viscous and capillary forces are ultimately the predominant forces. The process typically undergoes three phases: a first stage in which the droplet spreads, a second phase in which the area of contact with the solid substrate nearly remains constant, and a third stage in which the droplet retracts with its volume reaching zero finally. The objective of the investigation is to find the dynamics of spreading and absorption of the droplet using fundamentals while making relevant approximations to account for both radial and vertical dynamics. The proposed model requires minimal computational work. The results are compared with the published experimental data for the perfect wetting case, and are found to be in good agreement with detailed published experimental data for both droplet dynamics and dynamics of penetration in the porous substrate.

Automated summary

The study focuses on the dynamics of spreading and absorption of droplets on porous substrates through fundamental principles and relevant approximations, with minimal computational work required for the proposed model. Results are compared to published experimental data for perfect wetting, demonstrating good agreement for both droplet dynamics and penetration dynamics in the porous substrate.