Quantifying effective slip length over micropatterned hydrophobic surfaces

By P. Tsai, A. M. Peters, C. Pirat, Matthias Wessling, R. Lammertink, Detlef Lohse. 2009

193 citations recorded by the source corpus.

We employ microparticle image velocimetry to investigate laminar microflows in hydrophobic microstructured channels, in particular the slip length. These microchannels consist of longitudinal microgrooves, which can trap air and prompt a shear-free boundary condition and thus slippage enhancement. Our measurements reveal an increase in the slip length when the width of the microgrooves is enlarged. The result of the slip length is smaller than the analytical prediction by Philip [Z. Angew. Math. Phys. 23, 353 (1972)] for an infinitely large and textured channel comprised of alternating shear-free and no-slip boundary conditions. The smaller slip length (as compared with the prediction) can be attributed to the confinement of the microchannel and the bending of the meniscus (liquid-gas interface). Our experimental studies suggest that the curvature of the meniscus plays an important role in microflows over hydrophobic microridges.

Subfields: Biomedical Engineering, Computational Mechanics, Mechanical Engineering

View Paper: https://www.semanticscholar.org/paper/05f6daa73b4020d4441fd9e00a7ebc7d4553e9c9

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In Biomedical Engineering

In Computational Mechanics

In Mechanical Engineering

Citations in the corpus

Superhydrophobic drag reduction in laminar flows: a critical review (2016, methodology): “…3 176 Page 12 of 20 compared with the structural pitch) inside microchannel can contribute to a further decrease in slip length (Maynes et al. 2007; Tsai et al. 2009) under certain conditions, as predicted by analytical analyses (Sbragaglia and Prosperetti 2007a; Feuillebois et al. 2009) and…”
Superhydrophobic turbulent drag reduction as a function of surface grating parameters (2014, background): “It is noted that only micro particle image velocimetry (µPIV), whose spatial resolution is as small as O (1 µm), was able to measure discernible slips on SHPo surfaces in laminar (Joshep et al. 2006; Byun et al. 2008; Tsai et al. 2009) and turbulent (Daniello et al. 2009) flows.”
Advances in electrokinetics and their applications in micro/nano fluidics (2012, background): “For superhydrophobic surfaces with carefully designed roughness patterns, the apparent slip length can reach up to several microns (Joseph et al. 2006; Ou et al. 2004; Tsai et al. 2009) which can greatly enhance pressure-driven flows.”
On the mechanism of turbulent drag reduction with super-hydrophobic surfaces (2015, methodology): “These competing effects can result in either a small decrease (Tsai et al. 2009) or a small increase (Ou & Rothstein 2005), of no more than 5–10 %, in the magnitude of DR in laminar flow, compared to flat interfaces.”
Flow past superhydrophobic surfaces containing longitudinal grooves: effects of interface curvature (2010, methodology): “As L departs from zero, confinement effects (Tsai et al. 2009) due to the proximity of the top wall on the bottom superhydrophobic surface become important.”