Dynamics of motile microorganisms and entropy-optimized peristaltic flow in wavy microchannels with quadratic thermal radiation and Lorentz forces

Abstract Peristaltic transport phenomena play a crucial role in microscale thermal and biological fluid systems; however, efficient regulation of heat transfer, entropy generation, and microorganism dynamics under combined electromagnetic and radiative effects remains inadequately understood. In this study, peristaltic transport of a conducting fluid in a wavy microchannel is analyzed by incorporating the dynamics of motile microorganisms, quadratic thermal radiation, and Lorentz forces. A nonlinear mathematical framework is formulated to capture the coupled behavior of velocity, temperature, microorganism concentration, and entropy generation, and the resulting system is solved numerically under long-wavelength and low-Reynolds-number assumptions relevant to microfluidic applications. Mathematical models are formulated via incorporating electro-kinetic effects, thermophoresis and Brownian motion, and rheological performance of hyperbolic tangent fluid. The governing nonlinear equations are formulated and solved numerically using a finite element method. The results reveal that the Lorentz force significantly suppresses the axial velocity and enhances flow resistance, leading to a notable reduction in pumping efficiency, while simultaneously increasing entropy generation due to intensified electromagnetic dissipation. Quadratic thermal radiation is found to markedly elevate the temperature field, which in turn amplifies thermal irreversibility and alters the spatial distribution of motile microorganisms. An increase in microorganism concentration strengthens bioconvective effects, stabilizing the flow structure but contributing to higher entropy production through enhanced mass transfer irreversibility.