Instabilities due to microstructure growth at fluid interfaces

Tuesday, October 13, 2009 - 1:30pm - 2:10pm
EE/CS 3-180
Andrew Belmonte (The Pennsylvania State University)
Keywords: wormlike micelles, hydrodynamic instability, micellar aggregation reactions

Abstract: The viscoelasticity of a wormlike micellar fluid derives from the presence at the microscale of long tubelike surfactant aggregations (micelles), which occur at low concentrations due to the presence of an organic salt/cosurfactant. Without this salt the micelles are spherical, and the fluid is completely Newtonian. I will present recent experiments on hydrodynamic instabilities caused or modified by the formation of a viscoelastic micellar layer between two Newtonian liquids containing either the surfactant or the organic salt. The micellar reaction produces a fragile material which grows in competition with local stretching or advection at the interface, leading to new effects in Hele-Shaw fingering, in droplet sedimentation, and in microfluidic emulsions.
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