AI Insight
Researchers have investigated the phenomenon known as "viscous fingering," which occurs when a less viscous fluid (such as water) is injected into a more viscous fluid (such as soap), causing the thinner liquid to form finger-like channels that penetrate rather than uniformly displace the thicker fluid. The study identified physical parameters and conditions under which this instability can be reduced or controlled, potentially allowing for more efficient displacement of viscous fluids. Their findings suggest that factors such as injection rate, fluid viscosity contrast, and geometry of the containing vessel play key roles in determining whether viscous fingers form.
Why it matters
Controlling viscous fingering has significant practical implications for industries ranging from enhanced oil recovery, where water is used to push petroleum through rock formations, to pharmaceutical manufacturing and food processing, where efficient fluid displacement is critical to reducing waste and improving yield.
When they reach the bottom of a soap dispenser, frugal handwashers might try adding water to the bottle to push out the last bit of soap. But usually, the water drills right through the soap and jets out an only slightly sudsy splash.
Source: Physicists figure out how to reduce formation of 'viscous fingers'