Capillary imbibition in lubricant-coated channels

We present a theoretical and computational analysis of the  imbibition in a lubricant-coated pore. This simplified, schematic geometry is relevant for slippery liquid-infused porous surfaces (SLIPS) and lubricant-impregnated surfaces (LIS), where a lubricant film eliminates direct contact of the invading and displaced fluids with the solid. The study has clarified the relevance of the asymmetric distribution of dissipation among the  fluid phases in the imbibition process.  We identify two well defined spontaneous imbibition regimes: if dissipation is  more relevant in the displacing liquid, we recover the  diffusive advancing of the front corresponding to the well-known limit in which there is no lubricant. On the contrary, if dissipation takes place preferentially on the lubricant liquid, we find a linear advancing of the front through the entire channel

We present a  simplified mathematical model  that  captures these limiting regimes and quantifies the crossover between them. The model build on  a recent theoretical framework that identifies the relevant advancing regimes both for spontaneous and forced imbibition, as well as the corresponding crossovers.

This work provides a combined simulational and theoretical approach that paves the way into further scenarios of similar materials like lubricant-infused surfaces.