Fluid-induced resonances in vibrational and Brownian dynamics of a shear oscillator


We generally describe vibrational and Brownian dynamics of a shear oscillator interacting with a

confined Newtonian fluid. We show that the shear oscillator exhibits three characteristic dynamics in

viscous, weak inertial, and strong inertial regimes, and the dynamics are controlled by two system parameters,

effective confining height and oscillator-fluid coupling strength. While resonances of oscillators

are usually deteriorated in fluids, we interestingly find the resonances arisen in originally

overdamped oscillators, originated from hydrodynamic memory effects in strong inertial regime. The

present theory could be exploited for improving designs and performances of shear oscillators in fluids,

and reciprocally for investigating fluid properties by using shear oscillatory probes such as atomic force

microscope in shear-mode.