Mass transfer at the wall as a result of coherent structures in a turbulently flowing liquid

“…Perlmutter (I 961): Ruckenstein ( 1963): Harriott ( 1962): Koppel et al ( 1966): Bullin and Dukler (1972): Brodkey et al (1978): Street ( 1979): Komori et al (1982): Asher and Pankow ( 1991):…”

Section: Introductionunclassified

Latent and sensible heat flux predictions from a uniform pine forest using surface renewal and flux variance methods

Katul

Hsieh

Oren

et al. 1996

Boundary-Layer Meteorol

105

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A surface renewal model that links organized eddy motion to the latent and sensible heat fluxes is tested with eddy correlation measurements carried out in a 13 m tall uniform Loblolly pine plantation in Duke Forest, Durham, North Carolina. The surface renewal model is based on the occurance of ramp-like patterns in the scalar concentration measurements. To extract such ramp-like patterns from Eulerian scalar concentration measurements, a newly proposed time-frequency filtering scheme is developed and tested. The time-domain filtering is carried out using compactly-supported orthononnal wavelets in conjunction with the "Universal Wavelet Thresholding" approach of Donoho and Johnstone, while the frequency filtering is carried out by a band-pass sine filter centered around the ramp-occurrence frequency as proposed by other studies. The method was separately tested for heat and water vapour with good agreement between eddy correlation flux measurements and model predictions. The usefulness of the flux-variance method to predict sensible and latent heat fluxes is also considered. Our measurements suggest that the simple flux-variance method reproduces the measured heat and momentum fluxes despite the fact that the variances were measured within the roughness sublayer and not in the surface layer. Central to the predictions of water vapour fluxes using the flux-variance approach is the similarity between heat and water vapour transport by the turbulent air flow. This assumption is also investigated for this uniform forest terrain.

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“…To supplement these modeling approaches, analysts sometimes resort to empirical curve fitting, as in the recent paper by Kader (1981), or employ analogies between mass, heat and momentum transfer, with the turbulent Schmidt number simply set equal to unity. These various approaches are summarized by Sideman and Pinczewski (1975) and Brodkey et al (1978).…”

Section: Introductionmentioning

confidence: 99%

The surface rejuvenation theory of wall turbulence for momentum, heat and mass transfer: Application to moderate and high schmidt (Prandtl) fluids

1985

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The surface rejuvenation model of the turbulent burst process, already developed for the momentum and heat transfer processes, is applied to the field of mass transfer. The range of applicability of the theory, previously shown to be valid for the Prandtl number range 0.7 to 64 is extended to Schmidt numbers of 6,500 without introducing any new parameters. Concentration and temperature profiles for high Schmidt and Prandtl numbers are in agreement with experimental data. Theoretical expressions for Sherwood and Stanton numbers are calculated and shown to be in agreement with experimental data over five orders of magnitude. CONCLUSIONS AND SIGNIFICANCEA turbulent burst or surface rejuvenation model has been developed in this study for mass or heat transfer to fluids with values of Sc or Pr up to lo4. In this approach, the actual unsteady process that occurs between inrush and ejection phases of a burst event is modeled, with the approach distance distri- which is in agreement with experimental data for Sc from 0.5 to 10,000. The analysis indicates that the thickness of the unrepIenished layer of fluid existing at the surface is significant for values of Sc much greater than 5. For values of Sc less than about 5, this layer occupies less than 10% of the molecular wall region, such that the simple surface renewal model can be used.Based on the results of this analysis and on earlier work, it is concluded that the surface rejuvenation model provides a useful Page 1614October, 1985 AlChE Journal (Vol. 31, No. 10) alternative approach to characterizing the wall region for moderate to high values of Sc and Pr. Because of the strong physical basis for the surface rejuvenation model, and as this approach involves a minimum level of empiricism, the theory is believed to provide a fundamental basis for generalization to other transport processes involving wall turbulence.

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Mass transfer at the wall as a result of coherent structures in a turbulently flowing liquid

Cited by 15 publications

References 29 publications

Transfer processes in turbulent pipe flow described by the ERSR model

Transfer processes in turbulent pipe flow described by the ERSR model

Latent and sensible heat flux predictions from a uniform pine forest using surface renewal and flux variance methods

The surface rejuvenation theory of wall turbulence for momentum, heat and mass transfer: Application to moderate and high schmidt (Prandtl) fluids

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