The two-sided lid-driven cavity: Aspect-ratio dependence of the flow stability

The transition from two-dimensional (2D) steady to three-dimensional (3D) f low is investigated experimentally in a two-sided lid-driven cavity for ant i-parallel motion of two facing walls. Both wall speeds (Reynolds numbers) have the same absolute value. We present critical Reynolds numbers at the o nset of steady three-dimensional pout as a function of the cross-sectional aspect ratio. The critical curve is composed of different neutral branches belonging to different instability modes. Comparison with numerical results enables insight into the corresponding mechanisms.