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Published byGilbert Marsh Modified over 5 years ago

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The Brazil Nut Effect Modelling granular convection with bouncing balls By Richie Stauffer

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Granular Convection (Brazil Nut Effect) - The aggregate motion of granular particles (cereal, nuts, gravel, etc.) - When shaken, the larger particles tend to rise to the top of the mixture - The distribution is not random as one might expect (why don’t the heavier particles sink?) - So shaking your bag of breakfast cereal doesn’t help mix it! Explanations - Smaller grains fall in between cracks of the larger ones - The system tends towards a lower energy state by lowering the center of mass Implementation - Model circles with radius, mass, position, velocity - Move them at each time-step based on velocity and gravity - Detect intersections with walls and between circles, and model inelastic collisions - See what happens when you shake different sized balls Basic bouncing and collisions with velocities shown. The large Brazil nuts collect at the top, hence The Brazil Nut Effect. (Image: http://en.wikipedia.org/wiki/File:Mixed_nuts_small_white2.jpg )

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With no oscillation, all the circles settle as expected, with the larger ones on the bottom. When the floor starts shaking, the larger circles eventually make their way to the top. Implementation limitations: -overlaps occur due to imperfect collision engine -no friction -no other shapes Run my code with “circles”. Thanks!

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