Experimental study of turbulent transport of nanoparticles in convective turbulence

Abstract

We perform experimental study of turbulent transport of nanoparticles in convective turbulence with the Rayleigh number $\sim 10^8$ in the air flow. We measure temperature field in many locations by a temperature probe equipped with 11 E-thermocouples. Nanoparticles of the size $\sim 70$ nm in diameter are produced by Advanced Electrospray Aerosol Generator. To determine the number density of nanoparticles, we use Condensation Particle Counter. We demonstrate that the joint action of turbulent effects (which are important in the core flow) and molecular effects (which are essential near the boundaries of the chamber) results in an effective accumulation of nanoparticles at the cold wall of the chamber. The turbulent effects are characterised by turbulent diffusion and turbulent thermal diffusion of nanoparticles, while the molecular effects are described by the Brownian diffusion and thermophoresis, as well as the adhesion of nanoparticles at the cold wall of the chamber. In different experiments in convective turbulence in a chamber with the temperature difference $\Delta T$ between the bottom and top walls varying between $\Delta T=29$ K to $\Delta T=61$ K, we find that the mean number density of nanoparticles decreases exponentially in time. For instance, the characteristic decay time of the mean number density of nanoparticles varies from 12.8 min for $\Delta T=61$ K to 24 min for $\Delta T=29$ K. For better understanding of experimental results, we perform one-dimensional mean-field numerical simulations of the evolution of the mean number density of nanoparticles for conditions pertinent to the laboratory experiments. The obtained numerical results are in a good agreement with the experimental results.

arXiv comment10 pages, 7 figures, REVTEX4-2, revised

References in corpus (14)

• The clustering instability of inertial particles spatial distribution in turbulent flows
• Turbulent Diffusion and Turbulent Thermal Diffusion of Aerosols in Stratified Atmospheric Flows
• Tangling clustering of inertial particles in stably stratified turbulence
• Turbulent thermal diffusion in a multi-fan turbulence generator with the imposed mean temperature gradient
• Effect of large-scale coherent structures on turbulent convection
• Turbulent thermal diffusion of aerosols in geophysics and laboratory experiments
• Tangling clustering instability for small particles in temperature stratified turbulence
• Detection of turbulent thermal diffusion of particles in numerical simulations
• Turbophoresis in forced inhomogeneous turbulence
• Compressibility in turbulent MHD and passive scalar transport: mean-field theory
• Transition phenomena in unstably stratified turbulent flows
• Turbulent thermal diffusion in strongly stratified turbulence: theory and experiments
• Turbulent Thermal Diffusion: A Way to Concentrate Dust in Protoplanetary Discs
• Experimental study of temperature fluctuations in forced stably stratified turbulent flows

Cited by in corpus (3)

• Experimental study of turbulent thermal diffusion of particles in an inhomogeneous forced convective turbulence
• Large-scale clustering of inertial particles in a rotating, stratified and inhomogeneous turbulence
• Experimental investigation of turbulence and turbulent thermal diffusion in strongly inhomogeneous and anisotropic forced convection