Figure 6
From: Bubble cascade in Guinness beer is caused by gravity current instability
Velocity profiles of liquid phase in Guinness and in a particle suspension. (a) A typical snapshot of bubbles or tracer particles. Resin particles with 15 μm in diameter containing laser induced fluorescent (LIF) dye were used as tracer particles. (b) An instantaneous velocity vector field. The colour indicates the velocity along the wall. We treated bubbles in Guinness as behaving like tracer particle because of the small relative velocity between a bubble and the surrounding liquid phase as estimated by Eq. C 1. (c) Space-time diagrams for descending fluctuations. Velocities along the wall are plotted on the same scale as in (b).
