Experimental study of turbulent thermal diffusion in oscillating grids turbulence

Buchholz, James; Eidelman, A.; Elperin, T.; Grünefeld, Gerd; Kleeorin, N.; Krein, A.; Rogachevskii, I.

doi:10.1007/s00348-003-0770-2

Cited by 33 publications

(39 citation statements)

References 28 publications

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“…This effect is robust and the results of the numerical simulations are in agreement with theoretical studies [29,38], laboratory experiments [31,33,34] and atmospheric observations [35]. When St > 1, this effect is decreasing with Stokes number.…”

Section: Discussionsupporting

confidence: 85%

“…The phenomenon of turbulent thermal diffusion has been predicted theoretically in [29] and detected in different laboratory experiments in stably and unstably temperature-stratified turbulence [30][31][32][33][34]. This phenomenon is shown to be important for atmospheric turbulence with temperature inversions [35] and for smallscale particle clustering in temperature-stratified turbulence [34], but it is also expected to be significant for different kinds of heat exchangers, e.g., industrial boilers where Reynolds numbers and temperature gradients are large.…”

Section: Introductionmentioning

confidence: 90%

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Detection of turbulent thermal diffusion of particles in numerical simulations

et al. 2012

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The phenomenon of turbulent thermal diffusion in temperature-stratified turbulence causing a non-diffusive turbulent flux of inertial and non-inertial particles in the direction of the turbulent heat flux is found using direct numerical simulations (DNS). In simulations with and without gravity, this phenomenon is found to cause a peak in the particle number density around the minimum of the mean fluid temperature for Stokes numbers less than 1, where the Stokes number is the ratio of particle Stokes time to turbulent Kolmogorov time at the viscous scale. Turbulent thermal diffusion causes the formation of large-scale inhomogeneities in the spatial distribution of inertial particles. The strength of this effect is maximum for Stokes numbers around unity, and decreases again for larger values. The dynamics of inertial particles is studied using Lagrangian modelling in forced temperature-stratified turbulence, whereas non-inertial particles and the fluid are described using DNS in an Eulerian framework.

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Section: Discussionsupporting

confidence: 85%

Section: Introductionmentioning

confidence: 90%

Detection of turbulent thermal diffusion of particles in numerical simulations

et al. 2012

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“…TTD, first predicted theoretically by Elperin et al (1996) and then found in laboratory experiments (Buchholz et al, 2004), entails the transport of particles against the temperature gradient and is more effective at low pressure. Sofiev et al (2009b) showed that TTD is most likely responsible for the aerosol layer at tropopause height -a phenomenon not well explained so far.…”

Section: Thermal Diffusionmentioning

confidence: 91%

Online coupled regional meteorology chemistry models in Europe: current status and prospects

et al. 2014

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Published by Copernicus Publications on behalf of the European Geosciences Union. A. Baklanov et al.: Online coupled regional meteorology chemistry models in EuropeAbstract. Online coupled mesoscale meteorology atmospheric chemistry models have undergone a rapid evolution in recent years. Although mainly developed by the air quality modelling community, these models are also of interest for numerical weather prediction and regional climate modelling as they can consider not only the effects of meteorology on air quality, but also the potentially important effects of atmospheric composition on weather. Two ways of online coupling can be distinguished: online integrated and online access coupling. Online integrated models simulate meteorology and chemistry over the same grid in one model using one main time step for integration. Online access models use independent meteorology and chemistry modules that might even have different grids, but exchange meteorology and chemistry data on a regular and frequent basis. This article offers a comprehensive review of the current research status of online coupled meteorology and atmospheric chemistry modelling within Europe. Eighteen regional online coupled models developed or being used in Europe are described and compared. Topics discussed include a survey of processes relevant to the interactions between atmospheric physics, dynamics and composition; a brief overview of existing online mesoscale models and European model developments; an analysis on how feedback processes are treated in these models; numerical issues associated with coupled models; and several case studies and model performance evaluation methods. Finally, this article highlights selected scientific issues and emerging challenges that require proper consideration to improve the reliability and usability of these models for the three scientific communities: air quality, numerical meteorology modelling (including weather prediction) and climate modelling. This review will be of particular interest to model developers and users in all three fields as it presents a synthesis of scientific progress and provides recommendations for future research directions and priorities in the development, application and evaluation of online coupled models.

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“…In particular, the integral scale of turbulence is proportional to the distance from a grid, l∝Y, and the r.m.s. velocity is u 2 ∝f Y −1 (see for details, Buchholz et al, 2004, for air flow experiments). This implies that Reynolds numbers and the turbulent diffusion coefficient in the core of the flow are independent of the distances from the grid.…”

Section: Resultsmentioning

confidence: 99%

“…Equations (1) and (2) were derived using different methods by Elperin et al (1996Elperin et al ( , 1997Elperin et al ( , 2001), Pandya and Mashayek (2002) and Reeks (2005). First experiments in oscillating grids turbulence that demonstrated the phenomenon of turbulent thermal diffusion, were discussed by Eidelman et al (2004) and Buchholz et al (2004). Later, the phenomenon of turbulent thermal diffusion was observed in a multi-fan turbulence generator (Eidelman et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Experimental detection of turbulent thermaldiffusion of aerosols in non-isothermal flows

Eidelman

Elperin

Kleeorin

et al. 2006

Nonlin. Processes Geophys.

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Abstract. We studied experimentally a new phenomenon of turbulent thermal diffusion of particles which can cause formation of the large-scale aerosol layers in the vicinity of the atmospheric temperature inversions. This phenomenon was detected experimentally in oscillating grids turbulence in air flow. Three measurement techniques were used to study turbulent thermal diffusion in strongly inhomogeneous temperature fields, namely Particle Image Velocimetry to determine the turbulent velocity field, an image processing technique to determine the spatial distribution of aerosols, and an array of thermocouples for the temperature field. Experiments are presented for both, stably and unstably stratified fluid flows, by using both directions of the imposed mean vertical temperature gradient. We demonstrated that even in strongly inhomogeneous temperature fields particles in turbulent fluid flow accumulate at the regions with minimum of mean temperature of surrounding fluids due to the phenomenon of turbulent thermal diffusion.

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Experimental study of turbulent thermal diffusion in oscillating grids turbulence

Cited by 33 publications

References 28 publications

Detection of turbulent thermal diffusion of particles in numerical simulations

Detection of turbulent thermal diffusion of particles in numerical simulations

Online coupled regional meteorology chemistry models in Europe: current status and prospects

Experimental detection of turbulent thermaldiffusion of aerosols in non-isothermal flows

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