Second law analysis: electrically actuated flow of non-Newtonian fluids in wavy microchannels

We examined the energy production assessment for heat flow of non-Newtonian ionic liquids within a wavy microchannel, considering the impact of finite ionic size and electroosmotic actuation induced by the applied electric field. A numerical method based on the finite element approach was utilized to determine the associated flow, electrical-double layer potential, and temperature fields. The current model was validated against existing theoretical results. Entropy production, including viscous, thermal, Joule, and total entropy generation within the wavy microchannel, was explored by varying the Brinkman number, thermal Peclet number, steric factor for finite ionic size, Carreau number, and dimensionless amplitude. Increasing the Carreau number resulted in higher shear-thinning behavior of the liquid, leading to higher total entropy generation. Conversely, an increase in finite ionic size reduced entropy generation. Entropy generation decreased with increasing amplitude of the wavy wall. Notably, compared to the plane channel, wavy microchannels consistently exhibited reduced entropy generation. The insights gained from this study are relevant to the development of efficient heat-exchanging devices for electronic cooling.