Spiral Bubble Waves
We discovered this galaxylike pattern by chance while doing experiments with a high-viscosity (30,000 cSt) silicone oil at a high flow rate (0.14 mL per second) and low fall heights (3 to 4 cm). The spirals always have five branches. They occur because the center of the coil is not fixed but instead moves along a circular orbit of its own, creating crossing points between successive loops of the coiling rope where air bubbles are easily trapped. The position of the trapping point migrates slowly around a circle while previously formed bubbles are carried radially outward by the fluid spreading over the plate. It is the sum of these two motions that produces the spirals.