Numerical simulation of a partially ionized Oldroyd-B nanofluid flow driven by two homocentric rotating disks with motile microorganisms

Nanofluids are assumed to be an excellent source of enhanced heat transfer with advanced thermophysical characteristics. Nanofluids are the backbone of the heating and cooling in the industrial processes. This research delves into the dynamics of a partially ionized Oldroyd-B nanofluid flowing between stretchable rotating disks. The study investigates heat transfer mechanisms incorporating a modified Fourier law and convective heat conditions. The viscoelastic fluid model presented here allows for the examination of relaxation and retardation times. Furthermore, the heat and mass transport of the Oldroyd-B nanofluid is characterized using a Buongiorno model, which considers thermophoresis and Brownian diffusion effects. Additionally, the study explores the impact of gyrotactic microorganisms in nanofluids, potentially enhancing environmental management strategies. The governing equations transform into dimensionless forms using Von Karman similarity variables. Numerical investigation of the anticipated model is conducted using the bvp4c scheme in MATLAB. The variation of different parameters in the dimensionless equations is illustrated through graphs and in tabulated format. The results indicate that increasing thermophoresis and Lewis numbers lead to a decrease in fluid concentration. Moreover, the temperature of the fluid rises at the lower disk and declines at the upper disk relative to the Biot number. The proposed model is validated through comparison with closely related published work.