The Brazil Nut Effect Modelling granular convection with
bouncing balls By Richie Stauffer
Slide 2
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 dont the
heavier particles sink?) - So shaking your bag of breakfast cereal
doesnt 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
)
Slide 3
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!