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Title: Sustainability of apparent slip in micro-channel flows
Authors: Govardhan, RN
Pawar, PS
Bobji, MS
3rd Micro and Nano Flows Conference (MNF2011)
Keywords: Hydrophobic surface;Apparent slip;Drag reduction;Air pockets
Issue Date: 2011
Publisher: Brunel University
Citation: 3rd Micro and Nano Flows Conference, Thessaloniki, Greece, 22-24 August 2011
Abstract: In the present work, we experimentally study the flow of water over textured hydrophobic surfaces in a micro-channel. Shear stress measurements are done along with direct visualization of trapped air pockets on the hydrophobic surface. The trapped air pockets on such surfaces are known to be responsible for apparent slip at these surfaces and hence in significant drag reduction. In typical circumstances, the apparent slip reduces over time as seen, for example, from our shear stress measurements. This implies that the drag reduction will not be sustained. We have performed extensive visualizations of the trapped air pockets while varying flow parameters like the flow rate and the pressure. We present here direct visualizations that show that under some conditions, the air pockets can grow with time. The variation of the air pocket size with time is found to change qualitatively and quantitatively as the flow rate is varied. These measured changes in the air pocket size with time have a direct bearing on the sustainability of apparent slip in micro-channel flows.
Description: This paper was presented at the 3rd Micro and Nano Flows Conference (MNF2011), which was held at the Makedonia Palace Hotel, Thessaloniki in Greece. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, Aristotle University of Thessaloniki, University of Thessaly, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute.
ISBN: 978-1-902316-98-7
Appears in Collections:Brunel Institute for Bioengineering (BIB)
The Brunel Collection

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