(378a) Acoustic Streaming in Second Order Fluids

Acoustic streaming originated due to acoustic excitations in a fluid, is responsible for various applications such as heat transfer enhancement¹, particle manipulation^{2, 3}, cell sorting, fluid mixing⁴, enhancement in species transport⁵, etc. Acoustic streaming near a boundary i.e. inner streaming has mostly been studied for Newtonian fluids. This streaming is caused by the attenuation of the acoustic energy flux which gives rise to Reynolds stress divergence and generates the mean fluid motion. Here we have studied acoustic streaming in second order fluids. An asymptotic expansion for thin Stokes layer along with Nyborg’s perturbation approach^{6, 7} have been employed to derive analytical expressions for the primary oscillatory flow and steady acoustic streaming. It is observed that with increasing Deborah number (De), both the primary oscillatory flow and the acoustic streaming components get suppressed indicating a weak fluid mixing and/or heat transfer enhancement. The effect of Stokes layer compressibility on acoustic streaming has been studied and it is observed that a compressible Stokes layer provides higher acoustic streaming than an incompressible Stokes layer. The acoustic force density and the Stokes drift have also been calculated and its impact of particle manipulation have been studied for different Deborah number.

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