LAUSR

We discuss experimental investigations on steady streaming flows of dilute and semi-dilute polymer solutions in microfluidc devices. The effect of non-Newtonian behavior on steady streaming for different model fluids is determined by characterizing the evolution of the inner streaming layer with particle tracking velocimetry, as a function of oscillation frequency. We find that steady streaming velocity profiles in constant-viscosity elastic liquids are qualitatively similar to those in Newtonian liquids. Steady streaming velocity profiles in shear thinning liquids, however, display two unique features: (i) a non-monotonic behavior of the inner streaming layer with frequency, first increasing then decreasing in width, and (ii) a clear asymmetry in the flow profile at high frequencies.