Flow characteristics over an open rectangular cavity at high Reynolds number

Abstract In this study, the flow behavior over an open rectangular cavity is analyzed numerically and compared with existing experimental data. The influence of different Reynolds numbers ( Re = 10,000, 25,000, and 58,000) and cavity aspect ratios ( l / d = 1, 2, and 4) on flow dynamics is examined. A critical Reynolds number is identified, indicating a shift in flow behavior. For the l / d = 1 case, the recirculation zone inside the cavity interacts strongly with the downstream flow. In contrast, for l / d = 2 and 4, the main flow moves upward, and a distinct low-pressure region appears inside the cavity due to shear-layer roll-up. As the aspect ratio increases, the flow attaches more closely to the front wall, while the instabilities near the rear wall become more pronounced.