Heat and mass transfer analysis of MHD boundary layer flow with motile microorganisms over porous surfaces under variable wall thermal conditions

Abstract

• Introduces MHD boundary layer flow with variable wall thermal conditions. • Examines effects of motile microorganisms on heat and mass transfer. • Analyzes influence of magnetic field and porous medium on stability. • Provides new insights into bio-convective transport phenomena. • Results are applicable in biomedical and engineering heat systems. Nanotechnology plays an important role in improving several sectors due to its ability to improve heat and mass transfer processes, making it extremely important for modern engineering as well as scientific applications. The current study aims to investigate the boundary layer flow over a moving horizontal surface immersed in a nanofluid, while incorporating viscous dissipation, flexible heating wall effects, and the influence of gyrotactic microorganisms. To simplify the equations that govern the fluid dynamics, appropriate similarity transformations are employed to reduce them into the system of ODEs. The modified mathematical equations are solved numerically utilizing MATLAB’s built-in solvers bvp4c, which has been developed for boundary value problems. After validating the computational model, numerical simulations are performed to examine the axial velocity field, variation in temperature, nanoparticle concentration, and the density distribution of microorganisms, along with several other significant physical parameters. The effects of key variables including the temperature-dependent thermal conductivity index, porosity, magnetic field strength, Brownian motion coefficients, plate kinematics, and dimensionless numbers (Lewis, Peclet, Prandtl, and Eckert) are systematically evaluated and presented through graphical and tabular representations. The results indicate that elevating the temperature-dependent index improves the thermal gradient, consequently reducing the thermal boundary layer thickness. This research also holds potential applications in improving thermophysical properties such as viscosity, convective heat transfer efficiency, thermal conductivity, and diffusivity in base fluids like water and oil. As the field of nanofluid dynamics advances, future studies are expected to yield further innovations in this multidisciplinary domain.