Inuence d'un gradient de temp erature sur la stabilit e des rouleaux de Taylor

This experimental work concerns the inuence of a radial temperature gradient on the rst instability of a Couette{Taylor system with aspect ratio 114 and radius ratio 0:8. This study is about the identication of the eect of coupling between centrifugal force and torque induced by density radial stratication. The studied range of Grashof number is limited between 1500 and 1500 for a Prandtl number near 5.5. A spiral vortex o w appears due to the eect of a radial temperature gradient under Taylor vortices. Thanks to the analysis of complex demodulation, we have studied spatio{temporal properties of the pattern versus the control parameter.