Heat generation (absorption) in 3D bioconvection flow of Casson nanofluid via a convective heated stretchable surface

In the past few years, the bioconvection phenomenon has become increasingly important in various fields such as genetic systems, manufacturing, biotechnology, and ecological sciences. Bioconvection refers to the large-scale movement of fluid driven by a density gradient resulting from the collective spinning of microorganisms, like bacteria and algae. These self-propelled motile microorganisms increase the fluid's density as they swim in a coordinated direction, giving rise to the bioconvection phenomenon. The current study's goals are to investigate the characteristics of heat generation and absorption in a three-dimensional mixed bioconvection flow of Casson nanofluid inside a stretching cylinder. To analyze the system, a set of transformed nonlinear equations is numerically solved using the Runge-Kutta algorithm. The graphical representation helps explain the impact of different variables on physical properties. Notably, higher values of the Casson parameter are associated with increased viscosity and flow resistance, while a higher bioconvection Rayleigh number leads to elevated skin friction and motile density. Also, Skin friction is decreased by increasing the stretching and mixed convection characteristics. Heat generating processes achieve higher motile densities, Nusselt, and Sherwood amounts than heat absorbing processes.