Editing Granular convection (section)

== Study techniques ==
Granular convection has been probed by the use of [[magnetic resonance imaging]] (MRI),<ref>{{cite journal|title=Granular Convection Observed by Magnetic Resonance Imaging |doi=10.1126/science.267.5204.1632|year=1995|last1=Ehrichs|first1=E. E.|last2=Jaeger|first2=H. M.|last3=Karczmar|first3=G. S.|last4=Knight|first4=J. B.|last5=Kuperman|first5=V. Yu.|last6=Nagel|first6=S. R.|s2cid=29865605|journal=Science|volume=267|issue=5204|pages=1632–4|pmid=17808181|bibcode = 1995Sci...267.1632E }}</ref> where [[convection rolls]] similar to those in fluids ([[Bénard cell]]s) can be visualized.

Other studies have used time-lapse [[CT scan|CT scans]], [[Refractive index matching|refractive index matched]] fluids, and [[Positron emission tomography tracer|positron emission tracing]].<ref name=":0" />  On the lower-tech end of the scale, researchers have also used thin, clear plastic boxes, so that the motion of some objects is directly visible.<ref name=":0" />

The effect has been observed in even tiny particles driven only by [[brownian motion]] with no external energy input.<ref>{{Cite web |last=Warsaw |first=University of |title=Defying gravity with the Brazil nut effect |url=https://phys.org/news/2023-04-defying-gravity-brazil-nut-effect.html |access-date=2023-04-21 |website=phys.org |language=en}}</ref>