Gyrotactic mixed bioconvection flow of a nanofluid past a circular cylinder with convective boundary condition

• Published in: Journal of the Taiwan Institute of Chemical Engineers Vol. 99; pp. 9 - 17
• Main Authors: Rashad, A.M., Nabwey, Hossam A.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.06.2019
• Subjects: Circular cylinder; Gyrotactic microorganisms; Mixed bioconvection; Nanofluid; Gyrotactic microorganisms; Circular cylinder; Mixed bioconvection; Nanofluid
• ISSN: 1876-1070; 1876-1089
• DOI: 10.1016/j.jtice.2019.02.035

•Bioconvection of a nanofluid containing motile gyrotactic micro-organisms past a horizontal circular cylinder is described.•Mathematical modelling is performed based on Brownian movement and thermophoresis aspects.•Considerable enhancement in Skin friction is exhibited with larger thermophoresis parameter, buoyancy ratio parameter.•Density number of the motile micro-organisms is promoted with enhancement in the Brownian motion parameter.•The Nusselt number is promoted with enhancement in the Brownian motion parameter, bioconvection Schmidt number. In recent years, Bioconvection phenomenon plays a fundamental role in several applications like biological systems, modern engineering, biotechnology and environmental systems. The term bioconvection indicates to a macroscopic convection movement of fluid produced due to the density gradient generated by collective swimming of microorganisms like bacteria and algae. These self-propelled motile microorganisms enhance the density of the base fluid by swimming in a particular direction, thus causing bioconvection. This research describes the bioconvection of a nanofluid containing motile gyrotactic micro-organisms past a horizontal circular cylinder subject to convective boundary condition. Buongiorno's two-component nanofluid model is deployed with the Oberbeck–Boussinesq approximation. Modeling is based on Brownian movement and thermophoresis aspects. Boundary-layer idea is employed for simplification of governing expressions. Finite-difference algorithm is implemented for computations of nonlinear problems. Besides, velocity, temperature, motile micro-organism density function, local skin friction coefficient, Nusselt number, wall motile density gradient function are analyzed to variation in physically pertinent values of selected control parameters. Comparison amid the previously published results and the current numerical results are made for the limiting cases, which are found to be in an virtuous agreement. [Display omitted]