Listen up, coffee drinkers. Somebody has figured out why you spill your coffee on the way back to your desk. We’ll share, today on Engineering Works!
If you drink coffee, it’s happened to you. Your fresh cup of coffee has sloshed over the edge and onto the floor as you walk. Often, what’s going on is more than clumsiness, and fluid dynamics researchers have figured out what it is.
Fluid dynamics studies how forces affect the flow, or movement, of fluids. Today, the forces are the movements your cup makes as you walk. The fluid is your coffee. As you walk, you’ll see that both the cup and the coffee move quite a bit. This is where the spill starts.
The researchers analyzed high-speed video of people walking with cups of coffee and found that the cups moved in two different ways: big, regular motions as you walk, and smaller, irregular motions from uneven floors or when you get distracted.
Sometimes the movement of the cup reinforced the flow of the coffee — sort of like when you push your children in playground swings. If you push at just the right time, the swing goes higher. So does the coffee, until it sloshes over the rim of the cup.
The problem could be solved by changing the design of coffee cups so the coffee can’t move so much or so fast.
Our coffee cup works just fine, and we’ll see you next time.
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Start the discussion: Sometimes research like this seems pretty silly, but this could have implications beyond the coffee cup – anywhere you have liquids that move, in tanks or big pipes, say. Interesting stuff, we say.