Bioconvective entropy optimized flow of second-grade nanomaterial invoking nonlinear radiation

• Second-grade liquid model is studied. • Viscous dissipation, heat generation and Joule heating features are addressed. • Entropy generation rate is discussed. • Convective boundary conditions of heat, mass and motile organisms are addressed. • Mixed convective flow and thermal radiation is addressed. Engineers have shown much interest in study of nanomaterial flow. This is due to innovative features of nanomaterials for their applications in automotive technology, medicine, metal processing, power generation, renewable energy and many others. Heat transfer plays a crucial role in determining quality and finishing of final product. Therefore current study analyzes mixed convective and entropy generated flow of magnetized second grade nanoliquid. Steady flow is induced by stretched cylinder. Thermal expression comprised of radiation, heat generation/absorption, Ohmic heating, thermophoresis, viscous dissipation and Brownian movement features. Convective conditions for mass, gyrotactic microorganisms and heat transfer are accounted. Motile microorganism in first order chemically reactive flow is discussed. Appropriate transformations are adopted to obtain ordinary differential system. Solutions are computed numerically through BVP4C MATLAB. Behaviors of concentration, velocity, temperature and microorganisms fields are discussed. Outcomes for microorganism density number, gradient of concentration, skin friction coefficient and thermal transport rate are computed. Here liquid flow reduced for higher magnetic field whereas opposite scenario witnessed regarding thermal field and entropy rate. Decrease in liquid motion occurs through second-grade liquid variable while an increasing effect seen for thermal transport rate. Higher Prandtl number lead to intensify the thermal transport rate. Nusselt number and entropy rate for radiation have similar response qualitatively when compared with concentration through higher Soret number.