Consequences of substrate wettability on the hydro-electric energy conversion in electromagnetohydrodynamic flows through microchannel

In the present study, we attempt to analyse the consequences of substrate wettability on the hydro-electric energy conversion in electromagnetohydrodynamic flows through microchannel. In contrast to the traditional slip length based theoretical approach; we use a thermodynamically consistent phase-field based order parameter formalism to account for the near-wall surface-hydrophobicity mediated depletion layer formation. The research questions based on the knowledge gap we have addressed in this study are: Whether the consequences of magnetohydrodynamic forcing and surface wettability alter the development of streaming potential? To what extent the energy conversion efficiency gets affected for such microfluidic system? Towards this, we derive an expression for the induced streaming potential by considering nonlinear interaction between wall hydrophobicity, and superimposed magnetic field in the transverse direction of the flow. Notably, we have shown that hydrophobicity induced interfacial kinetics can contribute in remarkable enhancement of the induced streaming potential field. Our analysis also revealed that the magnetohydrodynamic effect may result in augmentations in the energy transfer efficiency under appropriate conditions. The analytical and numerical results presented in this work are expected to provide valuable guidelines towards optimizing the overall energy transfer performance of micro- and nano-systems by judicious employment of magnetohydrodynamic flows and hydrophobic substrate, and could be useful in further developments of theory, simulation, and experimental work.