Drop impact on a mesh - Viscosity effect.

Using a mesh surface is a promising technique in oil-water separation applications. In this paper, we investigated the dynamic impact of a silicone oil drop with different viscosities on an oleophilic mesh experimentally, which will help to define the critical conditions of the oil-water separation process. Four impact regimes were observed by controlling the impact velocity: deposition, partial imbibition, pinch-off, and separation. Thresholds of deposition, partial imbibition, and separation regimes were estimated, by balancing the inertia, capillary, and viscous forces. During the deposition and partial imbibition phenomena, the maximum spreading ratio (β) increases with the Weber number. In contrast, in the case of the separation phenomenon, no significant effect of the Weber number on β has been observed. Based on energy balance, we predicted the maximum elongation length of the liquid under the mesh during the partial imbibition phenomenon; the predicted data agrees well with the experimental data.