Acoustic streaming driven by immersed resonator structures

Sensors for fluid viscosity and density based on mechanical resonators are commonly modeled as linear systems, allowing a lumped element description as second order harmonic oscillators. To increase the signal-to-noise ratio it is advisable to maximize the oscillation amplitude. As a side effect, this leads to flow rectification known as acoustic streaming. To model this phenomenon we start with a harmonic analysis of the linearized fluid-structure interaction problem. From this solution the time-averaged rectification stresses (Reynolds stresses) are calculated and used as volume forces in a time-dependent laminar flow analysis. This method is applied to in-plane plate resonator structures and tuning fork resonators and compared to experimental investigations using high-speed flow visualization.