Experimental investigation of liquid slip

Abstract

The proliferation in technology has seen engineering applications reaching micro and nano scales. Understanding the boundary conditions describing the fluid flows is highly important since it has been proven that the controversial no-slip condition does not hold at these scales.

There are numerous factors identified to have influence over slip and the purpose of this project is to review them as well as conduct experiments to measure slips in microchannels.

An indirect approach to probe into the existence of liquid slip was adopted. Using hydrophobic PDMS microchannels and a simple set up, pressure drop and flow rate measurements were analytically computed to yield apparent slip velocity, shear rate and slip length. Results obtained from these experiments have indicated the presence of slip, which relates to lower friction (due to slippage) which in turn leads to lower pressures required to pump liquids and thereby saving energy.

It is recommended that further studies take into consideration factors such as temperature and dissolved bubbles to generate more accurate results.