Abstract
Patterns of convective flows produced by microorganisms swimming upward (namely, bioconvection) are investigated by numerical calculations of density model. The calculations suggests that there is a tendency for the aspect ratio of the convection cell to increase with Prandtl number. With respect to temporal change in bioconvection, the flow can be classified into three states (i.e. steady, unsteady, collapse). Comparing bioconvection to the bubble convection, another kind of particle-driven convection, there is similarity that steady-state and unsteady-state can be divided by Prandtl number, while difference is observed in the presence of the collapse pattern.
