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Updated: May 27, 2026
11:51
Visually Based Characterization of the Incipient Particle Motion in Regular Substrates: From Laminar to Turbulent Conditions
Published on: February 22, 2018
Scalar fluctuations from a point source in a turbulent boundary layer
1Defence R&D Canada Suffield, P.O. Box 4000 Station Main, Medicine Hat, Alberta, Canada T1A 8K6.
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|November 9, 2011
Summary
The concentration distribution of dispersing plumes from ground-level sources is accurately modeled using gamma distributions. This study predicts how the distribution parameter evolves downstream, incorporating mean shear effects.
Area of Science:
- Fluid dynamics
- Turbulence research
- Atmospheric dispersion modeling
Background:
- Understanding pollutant dispersal is crucial for environmental and safety assessments.
- Previous work suggested gamma distributions for confined mixing, but their application to open atmospheric plumes requires further investigation.
- The influence of atmospheric conditions like neutral stratification and wall-shear layers on plume concentration requires detailed study.
Purpose of the Study:
- To investigate the downstream concentration probability distribution of a dispersing plume.
- To determine if gamma distributions can effectively describe plume concentration in a wall-shear layer.
- To develop a prediction for the evolution of the gamma distribution parameter, including mean shear effects.
Main Methods:
- Analysis of plume dispersion from a continuous point source at ground level.
- Application of a one-parameter gamma distribution model to describe concentration probability.
- Derivation of a predictive model for the gamma distribution parameter (k).
Main Results:
- The concentration distribution along the plume centerline is well-described by a one-parameter gamma distribution.
- A prediction for the downstream evolution of the gamma distribution parameter (k) was successfully obtained.
- The prediction explicitly incorporates the impact of mean shear on the mean-square concentration.
Conclusions:
- Gamma distributions provide a robust model for plume concentration probability in neutral wall-shear layers.
- The developed prediction offers new insights into the dynamics of atmospheric dispersion.
- This research enhances the understanding of how turbulence and shear influence pollutant spread.
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