Granular convection

Granular convection is a phenomenon where granular material subjected to shaking or vibration will exhibit circulation patterns similar to types of fluid convection.^[1] It is sometimes called the Brazil nut effect,^[2] when the largest of irregularly shaped particles end up on the surface of a granular material containing a mixture of variously sized objects.^[3] This name derives from the example of a typical container of mixed nuts, in which the largest will be Brazil nuts. The phenomenon is also known as the muesli effect since it is seen in packets of breakfast cereal containing particles of different sizes but similar density, such as muesli mix.

Under experimental conditions, granular convection of variously sized particles has been observed forming convection cells similar to fluid motion.^[4][5]