Wettability patterning for managing liquid jets striking porous substrates*

Orthogonal liquid jet impingement on porous materials is important for applications such as heat transfer, filtration, and incontinence products. A desirable outcome of such situations is that the liquid does not penetrate the substrate at or near the point of jet impingement, but rather is spread over a wider area before it penetrates through. A wettability-patterning technique for altering the surface of a porous nonwoven matrix is presented in this work (Sen et al., ACS Appl. Mater. Interfaces, 2018). A water jet impinging orthogonally on such a substrate is distributed on the top surface and through the porous matrix, and is subsequently dispensed from prespecified points underneath the sample. The optimum design for uniform distribution of a liquid jet with flow rate exceeding 1 L/min with minimal or no spilling over the sample edges is identified. The effect of varying the impingement spot is also studied, and satisfactory performance even at offset impact conditions is observed.