Nonlinear dynamics of limiting current in the flow-modulated uniform-injection cell

We report on the dynamic response of limiting current when the uniform injection cell is subjected to large amplitude sinusoidal modulation of the electrolyte injection velocity. A general formalism for analyzing the linear and nonlinear system dynamics is used as the cornerstone of the theoretical and experimental work. Experimental measurements of the mean, linear, and lowest order nonlinear contributions to the modulated limiting current are found to agree reasonably well with theoretical predictions over the limited dynamic range achievable by the experimental apparatus. Theoretical results show that complicated nonlinear behavior arises from interactions between oscillating harmonics in the flow and concentration fields. For example, certain combinations of oscillation frequency, Reynolds number, and Schmidt number can create conditions where nonlinear harmonic interactions generate resonant or nullified response in specific nonlinear contributions to the limiting current.