Drag reduction for viscous laminar flow on spray-coated non-wetting surfaces

Siddarth Srinivasan, Wonjae Choi, Kyoo Chul Park, Shreerang S. Chhatre, Robert E. Cohen*, Gareth H. McKinley

*Corresponding author for this work

Research output: Contribution to journalArticle

85 Scopus citations

Abstract

We estimate the effective Navier-slip length for flow over a spray-fabricated liquid-repellent surface which supports a composite solid-air-liquid interface or 'Cassie-Baxter' state. The morphology of the coated substrate consists of randomly distributed corpuscular microstructures which encapsulate a film of trapped air (or 'plastron') upon contact with liquid. The reduction in viscous skin friction due to the plastron is evaluated using torque measurements in a parallel plate rheometer resulting in a measured slip length of bslip ≈ 39 μm, comparable to the mean periodicity of the microstructure evaluated from confocal fluorescence microscopy. The introduction of a large primary length-scale using dual-textured spray-coated meshes increases the magnitude of the effective slip length to values in the range 94 μm ≤ bslip ≤ 213 μm depending on the geometric features of the mesh. The wetted solid fractions on each mesh are calculated from free surface simulations on model sinusoidal mesh geometries. The trend in measured values of bslip with the mesh periodicity L and the computed wetted solid-fraction rs are found to be consistent with existing analytic predictions.

Original languageEnglish (US)
Pages (from-to)5691-5702
Number of pages12
JournalSoft Matter
Volume9
Issue number24
DOIs
StatePublished - Jun 28 2013

ASJC Scopus subject areas

  • Chemistry(all)
  • Condensed Matter Physics

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    Srinivasan, S., Choi, W., Park, K. C., Chhatre, S. S., Cohen, R. E., & McKinley, G. H. (2013). Drag reduction for viscous laminar flow on spray-coated non-wetting surfaces. Soft Matter, 9(24), 5691-5702. https://doi.org/10.1039/c3sm50445j