Particle dispersion in the near-wake of an isolated rotating wheel: Experimental and CFD study

• Characterisation of the fine particle dispersion in the wake of an isolated wheel of vehicle.
• Determination of mean velocity field of the air around the wheel.
• PM2.5 fraction behaviour investigated both experimentally and using CFD.
• Impact of the nature of tyre both on the velocity field of the flow and the particle dispersion.

The aim of the present study is the characterisation of the fine particle dispersion in the wake of an isolated wheel of vehicle. The work performed in this study lies within the description and the understanding of the transport of re-suspended road dust emissions induced by the circulation of vehicles. The behaviour of PM2.5 fraction in the field near to the wheel was investigated for two rotating velocities and two types of tyres, both experimentally and using Computational Fluid Dynamics (CFD). Experiments were carried out in a wind tunnel equipped by moving ground with carefully controlled aerodynamic conditions. CFD methods were used to calculate the velocity field of the air flow around a rotating wheel and to determine the trajectories for different particle sizes. The experiments reveal a strong impact of the nature of tyre both on the velocity field of the flow and the particle dispersion in the near wake of the wheel. In this simple case of an isolated wheel, the simulated flow was quite similar to the corresponding experimental results, although prediction of the flow located in the region of the point of contact between the wheel and the ground could be improved.