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The air supply of car passenger compartment is realized through the water box, receptacle collecting also rainwater streaming from the windshield. A better knowledge of air and water flows and instabilities produced inside the water box is necessary to ensure both good water draining outside the car and a feeding in fresh air, devoid of droplets inside. Results coming from this experimental view should allow to improve numerical models used by the firm. [ABSTRACT FROM AUTHOR]

The control by blowing techniques of longitudinal vortices originating at the rear pillars of a simplified automobile vehicle are analyzed by an experimental approach on the Ahmed body having a rear window angle of 25°. The experimental measurements are conducted according to stereoscopic Particle Image Velocimetry (Stereo-PIV). The results show that the blowing technique is associated to an increase of vorticity inside the vortex core on the upper part of the rear window and a decrease of vorticity on the lower part of the window. This vorticity drop is related to the onset of a recirculation zone (negative longitudinal velocities) in the vortex core which characterizes the vortex breakdown. The analysis of the azimuthal and longitudinal velocities allows to identify the increase of the Swirl number up to the critical point of vortex breakdown noted for high blowing velocities. [ABSTRACT FROM AUTHOR]

Flow through a cylindrical flat chamber, a model of some particular heat exchanger, is investigated numerically using the CFD-ACE code. Turbulence is modelled using the classical k–ϵ model. A better understanding of the secondary flow is then obtained: the k–ϵ model shows a strong dependence of the secondary flow velocity field with Reynolds number as was pointed out with precedent experimental results. Variations of the number of vortexes composing the secondary flow, giving a symmetrical or asymmetrical aspect, will influence the fluid particle trajectories and time residence. To cite this article: S. Petitot et al., C. R. Mecanique 330 (2002) 749–756. [Copyright &y& Elsevier]

We consider the isothermal flow through a cylindrical flat chamber, a model of some particular heat exchanger, for which LDV measurements and a numerical simulation have been performed. Experimental results show the establishment of an important vortex zone, the secondary flow extending all along the chamber radius. This observation leads to an expected significant increase of the fluid mixing. Results issued from the numerical simulation appear to be in close agreement with experimental data. Nevertheless, the k–ϵ model used here must be improved to obtain a better approach near the vortex centre. To cite this article: S. Petitot et al., C. R. Mecanique 330 (2002) 593–599. [Copyright &y& Elsevier]