Figure 8.

Distribution of squirmers in a monolayer and their velocity vectors. The computational cell is located at the centre as indicated by the solid lines. β is the ratio of second-mode squirming to first-mode squirming (cf. Ishikawa & Pedley 2008). (a) Aggregation of non-bottom-heavy squirmers with the areal fraction of 0.1 (β = 5). (b) Meso-scale spatio-temporal motion of non-bottom-heavy squirmers with the areal fraction of 0.5 (β = 5). (c) Band formation of bottom-heavy squirmers. Velocity vectors are taken relative to the average squirmer velocity, and vector g indicates the gravitational direction (β = 1).