Lagrangian stochastic modeling of a fluctuating plume in the convective boundary layer

Franzese, Pasquale

doi:10.1016/s1352-2310(03)00003-7

Cited by 61 publications

(77 citation statements)

References 21 publications

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“…However, there is still a large uncertainty on the value of i c at short distances. The numerical results by Franzese (2003) (not reported here) show a minimum at t * ϭ 0.4 and a maximum at t * ϭ 1.2, which are not present in our results. Franzese (2003) explained the presence of the maximum as a combination of two different effects: the decay of i c (in the plume's centerline) with distance from the source and the growth of i c with distance from …”

Section: ) Concentration Fluctuationscontrasting

confidence: 72%

“…At any distance t * from the source, the value of the ground concentration (and consequently the value of i c ) depends strongly on the plume spread z and the position of the plume mean height z. Since in the work by Franzese (2003) the value of z overestimates the experimental results, especially between 0.5 Ͻ t * Ͻ 2, the edge of the plume is located close to the ground. Since c reaches its maximum value at the plume's edges, as a result the value of i c may be overestimated.…”

Section: ) Concentration Fluctuationsmentioning

confidence: 98%

“…which is commonly used as parameterization for the plume horizontal mean position PDF (Yee and Wilson 2000;Luhar et al 2000;Franzese 2003) based on the water-tank experiment by Willis and Deardorff (1978). This result is explained by the homogeneity of the horizontal motion in the atmospheric CBL.…”

Section: B Meandering Componentmentioning

confidence: 99%

“…Both Luhar et al (2000) and Franzese (2003) distinguished between horizontal and vertical motion by assuming…”

Section: Concentrationmentioning

confidence: 99%

“…Although there is not a clear physical separation between large and small scales, Hanna (1986) showed that it is possible to represent a continuous spectrum of motions as a combination of two spectra with two main characteristic time scales: one corresponding to the motions that result in plume meander and the other related to relative dispersion. Gifford's analysis provided the basis for later studies (Yee et al 1994;Yee and Wilson 2000;Luhar et al 2000;Reynolds 2000;Franzese 2003), which incorporated in-plume fluctuations (that were neglected in Gifford's model) by specifying the PDF of the relative concentration, and took into account the inhomogeneous and skewed turbulence structure of the CBL by calculating the position of the plume centerline from oneparticle Lagrangian model trajectories. In all of these studies, the intensity of relative concentration fluctuations i cr is the key variable for the determination of the relative concentration PDF, but neither observational nor numerical data in the atmospheric CBL is currently available for an appropriate estimation of i cr .…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Statistics of Absolute and Relative Dispersion in the Atmospheric Convective Boundary Layer: A Large-Eddy Simulation Study

Dosio

Arellano

2006

Journal of the Atmospheric Sciences

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The influence of the different scales of turbulent motion on plume dispersion in the atmospheric convective boundary layer (CBL) is studied by means of a large-eddy simulation (LES). In particular, the large-scale (meandering) and small-scale (relative diffusion) contributions are separated by analyzing dispersion in two reference systems: the absolute (fixed) coordinate system and the coordinate system relative to the plume's instantaneous center of mass. In the relative coordinate system, the (vertically) inhomogeneous meandering motion is removed, and only the small-scale, homogeneous turbulent motion contributes to the dispersion process.First, mean plume position, dispersion parameters (variance), and skewness of the plume position are discussed. The analysis of the third-order moments shows how the structure and the symmetry of scalar distribution are affected with respect to the turbulent characteristics of the CBL (inhomogeneity of the large-scale vertical motion) and the presence of the boundary conditions (surface and top of the CBL). In fact, the reflection of the plume by the CBL boundaries generates the presence of nonlinear crosscorrelation terms in the balance equation for the third-order moments of the plume position. As a result, the third-order moment of the absolute position is not balanced by the sum of the third-order moments of the meandering and relative plume position.Second, mean concentration and concentration fluctuations are calculated and discussed in both coordinate systems. The intensity of relative concentration fluctuation i cr , which quantifies the internal (in plume) mixing, is explicitly calculated. Based on these results, a parameterization for the probability distribution function (PDF) of the relative concentration is proposed, showing very good agreement with the LES results. Finally, the validity of Gifford's formula, which relates the absolute concentration's high-order moments to the relative concentration and the PDF of the plume centerline, is studied. It is found that due to the presence of the CBL boundaries, Gifford's formula is not able to reproduce correctly the value of the absolute mean concentration near the ground. This result is analyzed by showing that, when the plume is reflected by the CBL boundaries, the instantaneous relative plume width zЈ 2 r (t) departs from its mean value 2 r . By introducing the skewness of the relative plume position into a parameterization for the relative mean concentration, the results for the calculated mean concentration are improved.

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Section: ) Concentration Fluctuationscontrasting

confidence: 72%

Section: ) Concentration Fluctuationsmentioning

confidence: 98%