The Cheerio Effect

Have you ever wondered why bits of cereal floating in milk tend to clump together or cling to the sides of a bowl? In fluid mechanics, this phenomenon is humorously called the "Cheerio effect," though it applies to any small, wettable object that floats, not just breakfast cereal. It is caused by a combination of buoyancy—the upward force a fluid exerts on an object of lower density—and surface tension—the elastic-like property of a liquid's surface. Where else might one observe this effect? More...