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- Experimental Study of a Ground VortexPublication . Barata, Jorge M M; Ribeiro, Samuel; Santos, Pedro José da Costa Teixeira; Silva, AndréLaser-Doppler measurements of the mean and turbulent components of the velocity flowfield resulting from the frontal collision of a wall jet with a boundary layer are presented and discussed, together with the visualization of the flow with direct photography and digital film imaging. The experiments were carried out for boundary-layer-to-wall- jet velocity ratios of 0.5 and 0.58. The results revealed the existence of a small counter-rotating recirculating zone located upstream (in the sense of the wall-jet flow) of the separation point, not reported before for this type of flow. This secondary vortex has an oscillating behavior observed in other ground-vortex flows, similar to that which can be observed, namely, through the bimodal histogram of the horizontal velocity (parallel to the wall) measurements, although the power spectra measurements do not exhibit any particular peaks.
- Experimental Study of a Ground Vortex: the Effect of the Crossflow VelocityPublication . Barata, Jorge M M; Bernardo, Nuno; Santos, Pedro José da Costa Teixeira; Silva, AndréLaser-Doppler measurements of the velocity characteristics of a ground vortex flow resulting from the collision of a wall jet with a boundary layer are presented and discussed together with flow visualization. In the present study velocity ratios between the boundary layer and the wall jet of 0.5 and 0.62 were considered. Two secondary vortices were found upstream the separation point for the highest velocity ratio. The angle of deflection of the upwash flow was found to decrease with the velocity ratio, while the wall jet penetration increases.