On the presence of odd transverse convective rolls in narrow-gap horizontal annuli

A numerical study of three-dimensional supercritical states of natural convection in a narrow-gap horizontal cylindrical annulus is presented. For the first time, an odd number of counter-rotating transverse rolls is shown to occur in a narrow-gap annulus. Flow and temperature fields associated with the odd roll state are compared to those of transverse roll states exhibiting even numbers of rolls, and factors influencing the occurrence and number of odd rolls are investigated. (C) 2002 American Institute of Physics.