http://prola.aps.org/abstract/PRL/v86/i15/p3423_1
Reverse Brazil Nut Problem: Competition between Percolation and Condensation Daniel C. Hong, Paul V. Quinn and Stefan Luding Phys. Rev. Lett. 86, 3423 - 3426 (2001)
In the Brazil nut problem (BNP), hard spheres with larger diameters rise to the