Mixed Convection in a Differentially Rotating Annulus

We investigate experimentally and numerically the influence of a radial temperature gradient in a vertical rotating cylindrical annulus. The geometrical parameters are fixed with aspect ratio and radii ratio respectively equal to 114 and 0.8. After imposing a Grashof number, the convection cell is destabilized by inertial forces due to the increasing of the rotation of the inner cylinder. Above a critical value of the control parameter, the Reynolds number, a spiral pattern occurs giving rise to a finite extent propagating pattern through a supercritical Hopf bifurcation.