Browsing by Author "Nunes, Ricardo F."
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- Unsteadiness of a Ground Vortex FlowPublication . Silva, André; Barata, Jorge M M; Santos, Pedro J. T. C; Nunes, Ricardo F.; Durão, DiamantinoThe impact zone of a wall jet with a boundary layer is studied computationally using a Reynolds averaged Navier-Stokes (RANS) approach with the "κ-ε" turbulence model. The computational domain corresponds to complete experimental rig and the measured boundary conditions were used. It was found that the gross features of the flow are well predicted, and the fluctuations of the flowfield around the ground vortex occur in a very small region near the wall where the impact between each flow occurs. The computational results showed a cyclic formation of two small secondary vortexes that appear and disappear cyclically around the separation and maximum penetration points of the ground vortex.
- Unsteady Computations of a Ground VortexPublication . Nunes, Ricardo F.; Silva, André; Barata, Jorge M MA computational study of the impact zone of a wall jet with a boundary layer was performed for a wide range of velocity ratios, VR, from 0.065 to 0.2. A ground vortex is formed and for intermediate velocity ratios the flowfield exhibits an oscillating behavior. The location and size of the ground vortex is almost constant during the complete sequence of oscillation, but secondary vortexes may also appear. For the case of very low velocity crossflow (small VR) the computations exhibit a stationary solution, which is in agreement with previous numerical and experimental results. For strong crossflows (large VR) the flow is also stationary, although there is a transition regime of some unsteadiness without any secondary vortex present.