The flow around three simplified models of side-view mirrors for automobiles is experimentally investigated by means of Robotic particle tracking velocimetry (PTV). The measurements are performed coupling a coaxial volumetric velocimeter with time-resolved three-dimensional (4D) Lagrangian Particle Tracking (LPT) data analyzed with the Shake-The-Box (STB) algorithm. Helium-filled soap bubbles were used as tracers in the wind tunnel experiment to achieve the measurement volume needed for characterizing the flow structures around and behind the models of automobile side-view mirrors. The aspect ratio of all the models is kept constant to H/W = 2. The effect of a slant angle at the front and the reduction of cross section at the model root are specifically investigated respectively using model 2 and model 3. In model 1 which represents generic geometry having semi-cylinder-spherical shape, the extension of the recirculation zone shrank in the z direction due to the free-end effect. When the flow is developing downstream, a vortex pair inclines towards the ground plane due to the downwash effect. This streamwise vortex shows a dipole distribution. In model 2 the trailing vortex does not fall toward downstream because a base vortex with opposite sign formed under the trailing vortex. This prevents the downwash flow from reaching the ground plane. In model 3, a streamwise vortex is generated from a strong upwash flow, which generates a short trailing vortex up to x/H = 1. This occurs because the vortex that was formed from the top and side end is suppressed and destroyed. The leg of the reverse U-shape structure of model 1 is almost perpendicular to the ground plane. However, in models 2 and 3, vortex shedding near the bottom is delayed, and an arch vortex is slightly slanted toward the model body.

Original languageEnglish
Article number110202
Number of pages11
JournalExperimental Thermal and Fluid Science
Volume119
DOIs
Publication statusE-pub ahead of print - 1 Nov 2020

    Research areas

  • Automobile, Coaxial volumetric velocimetry, Juncture flow, Lagrangian particle tracking, Robotic PTV, Shake-the-box algorithm, Side view mirror, Vortex structures

ID: 79712227