Unsteady Chemo-Tribological Squeezing Flow of Magnetized Bioconvection Lubricants: Numerical Study

Corrosion in lubricating systems involves many complex phenomena including chemical reaction, surfacial degradation, heat dissipation and unsteady effects. Biomimetic design is increasingly being employed in many branches of engineering (including tribology) and involves the mimicking of biological phenomena to achieve enhanced performance of systems. One such mechanism is known as bioconvection and characterizes micro-organism propulsion. Smart lubricants may exploit electromagnetic properties. Motivated by these developments, the current study examines the unsteady mixed bioconvection magnetohydrodynamic squeeing flow of a Newtonian lubricant doped with both gyrotactic micro-organisms and a species which is reactive, and intercalated between two surfaces squeezing together. No slip velocity conditions are imposed at the channel walls. The lubricant is chemically reactive and obeys a first order homogenous destructive reaction. The time-dependent conservation equations for mass (continuity), momentum, heat, species diffusion and motile micro-organism species are normalized with the aid of appropriate similarity transformations to yield a nonlinear, coupled, multi-degree ordinary differential boundary value problem (BVP). This BVP is solved using MATLAB bvp4c quadrature. Validation with earlier studies is included. Further verification of the MATLAB solutions is achieved with a successive Taylor series linearization method (STSLM) utilizing Chebyshev interpolating polynomials and Gauss-Lobatto collocation. The key parameters dictating the flow problem emerge as bioconvection Lewis number, bioconvection Péclet number (ratio of advection to diffusion of micro-organisms), Schmidt number, Prandtl number, magnetic body force parameter, reaction parameter, heat source/sink parameter and squeeze flow parameter. Selected computations for velocity, temperature, species concentration and motile micro-organism density function are visualized and exhibit considerable sensitivity to variation in most parameters. Detailed interpretation is included.