Rheological effects of micropolar slime on the gliding motility of bacteria with slip boundary condition

Ali, N; Asghar, Z; Beg, OA; Javed, T

Abstract

The gliding organisms are phylogenetically diverse with their hundreds of types, different shapes and several mechanism of motility. Gliding bacteria are rod-shaped bacteria without any flagella on their surface. They exhibit a creeping type of self-powered motion when nearly in contact with a solid surface. These bacteria leave an adhesive trail of slime and propel themselves by producing undulating waves in their body, which is one possible mode of motility for gliding bacteria. In the present study an undulating surface model is considered to discuss this type of bacterial locomotion. The classical Navier-Stokes equations are incapable of explaining the slime rheology at the microscopic level. Micropolar fluid dynamics however provides a solid framework for mimicking bacterial physical phenomena at both micro and nano-scales, and therefore in the present study, the constitutive equations of micropolar fluid are implemented to characterize the rheology of the slime. The flow equations are formulated under long wavelength and low Reynolds number assumptions. Exact expressions for stream function and pressure gradient are obtained. The speed of the gliding bacteria is numerically calculated by using a modified Newton-Raphson method. In addition, when the glider is fixed, the effects of micropolar slime parameters on the velocity, micro-rotation (angular velocity) of spherical slime particles, pressure rise per wavelength, pumping and trapping phenomena are also shown graphically and discussed in detail. The study is relevant to emerging biofuel cell technologies and also bacterial biophysics.

• Journal Article Type: Article
• Acceptance Date: Feb 27, 2018
• Online Publication Date: Mar 8, 2018
• Publication Date: Mar 8, 2018
• Deposit Date: Feb 28, 2018
• Publicly Available Date: Apr 4, 2018
• Journal: Results in Physics
• Electronic ISSN: 2211-3797
• Publisher: Elsevier
• Volume: 9
• Pages: 682-691
• DOI: https://doi.org/10.1016/j.rinp.2018.02.070
• Publisher URL: http://dx.doi.org/10.1016/j.rinp.2018.02.070
• Related Public URLs: https://www.journals.elsevier.com/results-in-physics/