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Consider an air-filled square cavity with cold top and bottom walls, adiabatic side walls and a centered heated sharp-edged source (a square-section cylinder). An unstable behavior has been highlighted previously while studying the effects of confinement (with different cylinder sizes) on the topology of the flow. A transition occurs from a bi-dimensional, steady regime to a three-dimensional, unsteady regime when the aspect ratio reaches the value of 0.4 for a Rayleigh number of 5.74 × 104 . Time-resolved 2D particle image velocimetry is used to characterize the dynamics of the flow in this configuration. The evolution of the instability is particularly investigated.Copyright © 2008 by ASME |