Direct numerical simulation of settling of a large solid particle during bioconvection

Abstract

SUMMARYSettling of a large solid particle in bioconvection ow caused by gyrotactic microorganisms is investigated. The particle is released from the top of the bioconvection chamber; its settling pattern depends on whether it is released in the centre of the bioconvection plume or at its periphery. The Chimera method is utilized; a subgrid is generated around a moving particle. The method suggested by Liu and Wang (Comput. Fluid 2004; 33:223-255) is further developed to account for the presence of a moving boundary in the streamfunction-vorticity formulation using the ÿnite-di erence method. A number of cases for di erent release positions of the particle are computed. It is demonstrated that bioconvection can either accelerate or decelerate settling of the particle depending on the initial position of the particle relative to the plume centre. It is also shown that the particle impacts bioconvection plume by changing its shape and location in the chamber.

Dynamics of large solid particles in bioconvective sedimentation

“…Geng and Kuznetsov [10,11] investigate the sedimentation of small solid particles in bioconvection. Sedimentation of a single large particle during bioconvection is studied in Reference [12].…”

“…At the surface of the settling particles, the no-slip boundary condition is imposed. Geng and Kuznetsov [12] have shown that the values of the streamfunction and vorticity on a moving boundary in a multi-connected domain can be calculated numerically by the following procedure.…”