The core principle governing unidirectional transport in oscillatory systems is that momentum diffusion and inertial forces interact to determine velocity profiles under time-periodic forcing, quantified by the dimensionless Reolds number (or Reynolds based on frequency), which represents the ratio of diffusive time scales to oscillation periods. In the limit where this parameter is small, the system behaves quasi-steadily with linear profiles responding instantaneously to surface velocities, whereas a large parameter induces boundary layer confinement characterized by an exponentially decaying penetration depth and phase shifts between driving and response fields due to inertial effects.
The core principle governing unidirectional transport in oscillatory systems is that momentum diffusion and inertial forces interact to determine velocity profiles under time-periodic forcing, quanti…