振荡栅格湍流中的湍动热扩散实验研究
Abstract We have experimentally detected a new effect,turbulent thermal diffusion, as predicted theoretically byElperin et al. (Phys Rev Lett (1996) 76:224–228) andassociated with the turbulent transport of inertial particles.The essence of this effect is an appearance of a non-diffusivemean flux of particles in the direction of the meanheat flux. This results in formation of large-scale inhomogeneitiesin the spatial distribution of inertial particlesthat are accumulated in regions of minimum mean temperaturein the surrounding fluid. The experiments wereperformed in oscillating grids turbulence with an imposedmean temperature gradient. We used Particle ImageVelocimetry to determine the turbulent velocity field, andan Image Processing Technique based on the analysis ofthe intensity of the Mie scattering to determine the spatialdistribution of tracer particles. Analysis of the intensity oflaser light Mie scattering by tracer particles showed thatthe tracer particles accumulate in the vicinity of the minimumof the mean temperature. The latter finding confirmsthe existence of the effect of turbulent thermaldiffusion.