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Air entrainment in hairy surfaces

Alice Nasto1, Marianne Regli1, P.-T. Brun2, José Alvarado1, Christophe Clanet3, and A. E. Hosoi1,2

  • 1Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
  • 2Department of Mathematics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
  • 3Ladhyx, UMR No. 7646 du CNRS, École Polytechnique, 91128 Palaiseau CEDEX, France

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Phys. Rev. Fluids 1, 033905 – Published 29 July, 2016

DOI: https://doi.org/10.1103/PhysRevFluids.1.033905

Abstract

Motivated by diving semiaquatic mammals, we investigate the mechanism of dynamic air entrainment in hairy surfaces submerged in liquid. Hairy surfaces are cast out of polydimethylsiloxane elastomer and plunged into a fluid bath at different velocities. Experimentally, we find that the amount of air entrained is greater than what is expected for smooth surfaces. Theoretically, we show that the hairy surface can be considered as a porous medium and we describe the air entrainment via a competition between the hydrostatic forcing and the viscous resistance in the pores. A phase diagram that includes data from our experiments and biological data from diving semiaquatic mammals is included to place the model system in a biological context and predict the regime for which the animal is protected by a plastron of air.

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Information

Phys. Rev. Fluids 1, 033905– Published 29 July, 2016
  • Received 18 March 2016
Article part of CHORUS

©2016 American Physical Society

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