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 by
Elperin et al. (Phys Rev Lett (1996) 76:224228) and
associated with the turbulent transport of inertial particles.
The essence of this effect is an appearance of a non-diffusive
mean flux of particles in the direction of the mean
heat flux. This results in formation of large-scale inhomogeneities
in the spatial distribution of inertial particles
that are accumulated in regions of minimum mean temperature
in the surrounding fluid. The experiments were
performed in oscillating grids turbulence with an imposed
mean temperature gradient. We used Particle Image
Velocimetry to determine the turbulent velocity field, and
an Image Processing Technique based on the analysis of
the intensity of the Mie scattering to determine the spatial
distribution of tracer particles. Analysis of the intensity of
laser light Mie scattering by tracer particles showed that
the tracer particles accumulate in the vicinity of the minimum
of the mean temperature. The latter finding confirms
the existence of the effect of turbulent thermal
diffusion. 德国LaVision PIV/PLIF粒子成像测速场仪