Thermal and flow analysis of MHD nanofluid between oscillating discs with motile microorganisms: Application in rotating bioreactors

Efficient heat and mass transfer is critical in many engineering applications, such as cooling systems and energy devices, where nanofluids have emerged as promising working fluids due to their enhanced thermal properties. This study focuses on the time-dependent magnetohydrodynamic (MHD) flow of nanofluids influenced by motile microorganisms between two spinning discs, a configuration relevant to rotating machinery and bioengineering processes. The impact of Hall current, magnetic field and heat source on the bioconvective nanofluid flow are investigated by formulating a system of nonlinear partial differential equations describing velocity, temperature, nanoparticle concentration, and microorganism density. These equations are solved numerically using the MATLAB bvp4c solver with the aid of the shooting approach. The results reveal that Hall currents increase the velocity field, whereas magnetic field effects diminish as the upper disc moves downward. Furthermore, upward rotation of the upper disc enhances the temperature distribution, and microorganism density decreases as increases from 0.1 to 3.0, while for an increase in Peclet number values i.e. ( = 2.0, 2.3, 2.6, 2.9) the profile get stronger which highlights complex interactions in the flow. The findings contribute to improved thermal management strategies in engineering systems such as gas turbines, rotating machinery, and biomedical devices where enhanced heat and mass transfer are essential.