LAUSR

The oscillatory instability of 2D natural convection flow in a cooled square enclosure with a tandem of vertically aligned cylinders was investigated in detail. The study was performed by applying linear stability analysis and time integration of slightly perturbed flows. As a function of the distance between the two cylinders the flow underwent a transition to unsteadiness via either a symmetry-breaking or a symmetry-preserving first Hopf bifurcation. The critical values of the Rayleigh number Racr and the oscillatory instability ωcr for the transition to unsteadiness were accurately estimated. An extensive discussion of the scenarios determining the mechanisms driving the onset of the observed instabilities is presented.