Magneto-bioconvection flow in an annulus between circular cylinders containing oxytactic microorganisms.

The present work focuses on the numerical investigations of the existence of oxytactic microorganisms on the bioconvection flow of nano-encapsulated phase change material (NEPCM) inside an annulus. The novel geometry of an annulus contains an inner wavy cylinder and an outer circular cylinder considering a rotational circular velocity of an inner wavy cylinder. The incompressible smoothed particle hydrodynamics (ISPH) method solved the dimensionless form of controlling equations. The novel annulus between the embedded circular cylinder and the outer circular cylinder can be applied in the tube bundles in heat exchangers. Further, rotation of an inner wavy cylinder in a circular cavity can be used in thermal fin's vibration and cooling of the electric devices. The effects of pertinent parameters such as a rotational frequency number ω , bioconvection Rayleigh number Ra b , thermal radiation Rd , Lewis number Le , and Hartmann number Ha on the contours of oxygen concentration ϕ , temperature θ , heat capacity ratio Cr , oxytactic microorganisms N , and velocity field V as well as the average Nusselt & Sherwood numbers Nu ¯ and Sh ¯ are conducted. Increasing ω enhances the maximum of V by 56.6% and lowers Nu ¯. The variations of Ra b are enhanced the contours of N and maximized the velocity field from 0.86 at Ra b = 1 to 8.22 at Ra b = 100 due to the power in bioconvection flow. Increasing Le diminishes the strength of oxygen concentration ϕ and microorganisms N. Increasing Ha from 0 to 50 slows down the velocity field's maximum by 47.2 % and enhances the value of Nu ¯. [ABSTRACT FROM AUTHOR]