How many oranges can you remove from an angled fruit display before they all tumble down in a fruit avalanche? For 2370 of them, at an angle of 20 degrees with respect to the horizontal, the answer is 190 oranges.
This is one of the results of a series of simulations to work out under what conditions a fruit display will come tumbling down, run by at O鈥橦iggins University in Chile and his team. 鈥淚 hear colleagues talk about avalanches in geophysics a lot, so when I鈥檓 at the market, picking fruit, I鈥檓 often thinking about the stability of the whole pile,鈥� he says.
The researchers simulated a collection of small spheres arranged in a honeycomb pattern inside a tilted box 鈥� an idealised version of a single-layer display of oranges at a supermarket. They then simulated randomly removing one sphere at a time to see what would happen.
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After each removal, they gave the display 3 seconds to settle into a new arrangement. When more fruits tried to roll past the fence that held them in place than resettle, the computer recorded an avalanche.
The team found that avalanches never happen if the display is angled less than 16 degrees. For angles close to 20 degrees, an avalanche is inevitable when each fruit touches four or fewer others on average. Overall, the proportion of fruit that needed to be removed to cause an avalanche was fairly consistent, at around 9 per cent of the fruit in a display angled between 18 and 22 degrees.
at the University of Liege in Belgium says that removing items in the display disrupts the series of forces that act between each pair of items, and this disruption leads to collapse. 鈥淪mall action, big consequences is the avalanche motto,鈥� he says.
The new study captures this phenomenon, but Dorbolo says there are more details that could be accounted for, like different amounts of friction between different adjacent fruits. Two smooth peppers touching isn鈥檛 the same as two bumpy avocados, for example.
The fruit display is a simple system, says Gutierrez, but researchers could use it as a first step in building more elaborate avalanche models. His team is planning to simulate displays with more than one layer. These simulations could be more like snow avalanches, where snow and ice move in layers rather than one small piece at a time.
Reference: arXiv,
