Details of Grant 

EPSRC Reference:	EP/D500826/1
Title:	Drag Reduction & Slip at Solid-Liquid interfaces
Principal Investigator:	McHale, Professor G
Other Investigators:	Perry, Professor C Newton, Dr MI
Researcher Co-Investigators:
Project Partners:
Department:	School of Science & Technology
Organisation:	Nottingham Trent University
Scheme:	Standard Research (Pre-FEC)
Starts:	01 October 2005	Ends:	31 January 2009	Value (£):	205,498
EPSRC Research Topic Classifications:	Surfaces & Interfaces
EPSRC Industrial Sector Classifications:	Aerospace, Defence and Marine
Related Grants:
Panel History:
Summary on Grant Application Form
It is usually assumed that for a liquid, such as water, flowing over a solid surface the appropriate boundary condition at the solid-liquid interface is that the speed of the liquid should match that of the solid wall, i.e. there is no-slip at the boundary. However, over the last four years there has been a growing body of high quality experimental evidence for a hydrodynamic slip boundary condition at interfaces when the boundary is either hydrophobic and/or the channels are microscopically narrow. The techniques used to provide this experimental evidence have included surface force apparatus (SFA), modified atomic force microscopy (AFM) and fluorescence recovery/near field laser velocimetry. The conclusions from these experiments have been supported by molecular dynamics simulations and by theoretical arguments. In particular, work on flow over a super-water repellent solid has suggested a reduction in flow resistance of around 15% which was described by a slip boundary condition with a truly colossal slip length of greater than 250 microns. Whilst the concept of real slip remains controversial, what is clear is that in the majority of these experiments surface roughness and the hydrophobicity of the interface are essential ingredients in generating results consistent with an apparent slip boundary condition. In this project we will create super-hydrophobic solid surfaces and investigate experimentally the flow over them to quantify the relationship between slip length and the roughness and hydrophobicity of the surface.
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Organisation Website:	http://www.ntu.ac.uk