Bioconvection of Couple Stress Fluid in a Channel with Expanding or Contracting Walls

Abstract

This paper deals with the flow of an incompressible couple-stress fluid containing gyrotactic microorganisms in a channel with expanding or contracting porous walls. The bio-convection in couple stress fluid is advantageous to study various kinds of physical problems since couple stress fluid model can explain the rheology of various complex fluids, such as polymeric suspension, lubricants, liquid crystals, and blood. The governing equations are reduced to a system of non-linear ordinary differential equations using similarity transformations, linearized using successive linearization method and then solved using the Chebyshev collocation method. The influence of couple stress fluid parameters and other pertinent physical parameters on the motile microorganism distribution and density number of motile microorganism is examined.