Cilia induced transport of microorganisms in Bingham plastic fluid with wall slip in asymmetric microchannel.

Abstract

Bingham plastic fluids are frequently found in both biological and industrial contexts, especially in situations requiring the movement of mucus, chyme, or blood that has unusual viscosity through microchannels. Inspired by the function of cilia-driven peristalsis in biological transport, this research presents a new mathematical model for the peristaltic motion of a Bingham plastic fluid that contains active microorganisms within an asymmetric microchannel incorporating slip boundary effect. The primary partial differential equations governing momentum, heat, concentration, and the transport of microorganisms are transformed into a non-dimensional format based on the assumptions of long wavelength and low Reynolds number. By utilizing suitable scaling parameters, the system is simplified to a pair of nonlinear ordinary differential equations. The slip effects are included along the channel walls, and the cilia-induced movement is represented through parameters relating to eccentricity and cilia length. The obtained equations, together with the relevant boundary conditions, are solved numerically using the bvp4c method in MATLAB. The findings indicate that slip increases the velocity near the walls of the channel, but decreases it in the core of the channel. A rise in the Bingham number diminishes fluid trapping, whereas a greater eccentricity enhances pumping efficiency by decreasing recirculating bolus regions. The temperature rises due to heat generation and Joule heating but is lowered by thermal radiation and heat sink effects. Concentration declines with an increase in Schmidt number and chemical reactions, while the density of microorganisms decreases with thermophoresis, bioconvection constant, and Peclet number. The novelty of this study lies in integrating the Bingham plastic rheology with cilia-induced wall motion, slip effects, and microorganism transport in an asymmetric channel. This fills a gap in the existing literature where such a combination has not been previously addressed, despite its strong relevance to physiological flows such as mucus clearance, chyme transport, and biomedical peristaltic pump design.