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A Model of Bioconvection of a Dilute Suspension of Gravitactic Microorganisms in an Isotropic Porous Medium


 A new continuum model is formulated for bioconvection in a dilute suspension of swimming, gravitactic microorganisms in a porous medium. ‘Bioconvection’ is the name given to pattern-forming convective motions set up in suspensions of swimming microorganisms. ‘Gravitaxis’ describes the way of the swimming and means that microorganisms tend to swim against the gravity. The aim of this paper is to analyze collective behaviour and pattern formation in populations of swimming microorganisms. The existence and stability of a two-dimensional plume in a tall, narrow chamber with stress-free sidewalls is investigated. Governing equations include the Darcy law and the microorganism conservation equation. A conservative finite-difference scheme is used to solve these equations numerically.