Abstract
Convective patterns of silicone oil in a plane Couette flow were observed for various vertical shears and at various Rayleigh numbers. A circular channel with a rotating upper disk was used to produce a shear flow and convective motions were generated by heating the bottom and cooling the top of the channel. The result indicates that there are three convective regimes: cellular patterns which appear at large Rayleigh numbers and for small vertical shears, longitudinal rolls which appear at small Rayleigh numbers and for large vertical shears and intermediate convective patterns in the domain between the cellular and longitudinal-roll regimes. The critical shear which separates longitudinal rolls from cellular patterns increases with the Rayleigh number. The transverse rolls were not observed in the range of the vertical shear considered here. The phase velocity of the convective cells was found to be about one half of the velocity of the upper disk.
The transition of convective patterns was observed using a modified channel which has irregularities at the bottom surface to enhance the occurrence of the transverse rolls. It was found that the critical shear is increased by the presence of the bottom irregularities and that existence of transverse rolls with a large amplitude at the initial state did not change characteristics of the convective regimes.
