Droplet impingement and wetting behavior on a chemically heterogeneous surface in the Beyond-Cassie-Baxter regime

GN Yi and ZQ Cai and ZM Gao and ZC Jiang and XB Huang and JJ Derksen, AICHE JOURNAL, 66, e16263 (2020).

DOI: 10.1002/aic.16263

Droplet impingement and anisotropic wetting on chemically heterogeneous stripe-patterned surfaces is simulated by means of many-body dissipative particle dynamics. The ratio of the stripe width and initial droplet diameter, defined as beta, ranges from 0.5 to 1.0 so that the wetting process is in the Beyond-Cassie-Baxter regime and is highly anisotropic. At zero Weber number (that is, without considering droplet inertia) and with superhydrophobic stripes, beta is the only factor affecting the droplet perpendicular contact angle and aspect ratio. For inertial droplets, beta and the Weber number are found to have an effect on the eventual droplet morphology on multi-striped surfaces. These morphologies include elongated shape, split-off, and "butterfly" shape. A correlation for critical split-off conditions has been determined. An energy analysis of droplet impingement shows that the normalized surface energy of the droplet is independent of the Weber number if the droplet is elongated or butterfly-shaped.

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