8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

P7.106Thu 811:10-14:00The Saffman-Taylor instability in colloid-polymermixturesSiti Aminah Setu 11 University of Oxford, Physical & Theoretical Chemistry Laboratory, South Parks RoadOX1 3QZ, Oxford, United KingdomWhenever a low viscosity fluid displaces a high viscosity fluid in a porous medium or Hele-Shawcell, the interface is rendered unstable. We show that this so-called Saffman-Taylor instability persistsin systems where the interfacial tension is roughly a million times lower than in molecularsystems. As our model system we use a mixture of spherical colloids and non-adsorbing polymers,which we study by means of confocal laser scanning microscopy in microfluidic devices. Itturns out that at these scales thermal fluctuations, wettability and gravity all play a crucial role indescribing the instability.106