Journal ArticleDOI
Criteria for the selection of stochastic models of particle trajectories in turbulent flows
TLDR
In this paper, the relationships between the various criteria are examined for a very general class of models and it is shown that most of the criteria are equivalent and also how a model can be designed to satisfy these criteria exactly and to be consistent with inertial-subrange theory.Abstract:
Many different random-walk models of dispersion in inhomogeneous or unsteady turbulence have been proposed and several criteria have emerged to distinguish good models from bad. In this paper the relationships between the various criteria are examined for a very general class of models and it is shown that most of the criteria are equivalent. It is also shown how a model can be designed to satisfy these criteria exactly and to be consistent with inertial-subrange theory. Some examples of models that obey the criteria are described. As an illustration some calculations of dispersion in free-convective conditions are presented.read more
Citations
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Footprint Estimation for Multi-Layered Sources and Sinks Inside Canopies in Open and Protected Environments
TL;DR: In this article, a multi-layered flux footprint model is developed for a canopy situated within a protected environment such as a screenhouse, which accounts for the vertically distributed sources and sinks within the canopy as well as modifications introduced by the screen on the flow field and micro-environment.
Journal ArticleDOI
A Homogeneous Langevin Equation Model, Part i: Simulation of Particle Trajectories in Turbulence with a Skewed Velocity Distribution
John S. Nasstrom,Donald L. Ermak +1 more
TL;DR: In this article, a Lagrangian stochastic model for the time evolution of the velocity of a fluid particle is presented, which is based on a one-dimensional generalized Langevin equation, and assumes the velocity probability distribution of the turbulent fluid is skewed and spatially homogeneous.
Journal ArticleDOI
Implementation of a Lagrangian Stochastic Particle Trajectory Model (LaStTraM) to Simulate Concentration and Flux Footprints Using the Microclimate Model ENVI-Met
TL;DR: The Lagrangian Stochastic Trajectory Model (LSTM) as mentioned in this paper is a post-processing tool, which uses simulation results of the holistic 3D microclimate model ENVI-met as input.
The Transport and Degradation of Floral Scent Plumes: Ecological Ramifications from a Modeling Perspective
Abstract: The symbiotic relationship between flowering plants and nectar gathering insects is an essential ecological process, responsible for pollination and healthy insect colonies. Floral scents, composed of a variety of volatile compounds, have been shown to mediate plant-pollinator interactions by attracting foraging species towards rewarding nectar sources. Because of their volatile nature, however, floral scents will react readily with anthropogenic air pollutants, resulting in a continual degradation of plumes downwind of floral patches. In order to investigate this degradation, a three dimensional, stochastic Lagrangian diffusion model was developed to represent the turbulent dispersion and reaction of floral scent plumes within the turbulent atmospheric surface layer. Additionally, the potential impact on foraging insects was investigated by utilizing a random walk model in order to simulate search behavior, which was then incorporated into the dispersion model. Results indicate that search times could be significantly increased in polluted conditions due to considerable plume degradation and changes in the composition of the floral scent. Model results indicate that this ecological system is sensitive to changes in air quality, especially if species are unable to adapt. The ability to communicate with members of the hive and share knowledge of rewarding sources, however, has been shown to reduce the impacts of scent plume degradation. For solitary species, this added stress could have cascading impacts on the fitness of foraging species due to less time being devoted to other necessary tasks within the hive, and possible nectar shortages because of increased competition.
References
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Journal ArticleDOI
An Introduction to Probability Theory and Its Applications.
Journal ArticleDOI
Turbulence Structure in the Convective Boundary Layer
TL;DR: In this paper, a boundary layer experiment conducted over a flat site in northwestern Minnesota is discussed, where wind and temperature fluctuations near the ground were measured with AFCRL's fast-response instrumentation on a 32 m tower with MRU probes attached at five different heights to the tethering cable of a 1300 m2 kite balloon.
Book
Theory and Applications of Stochastic Differential Equations
Zeev Schuss,Robert O'Malley +1 more
TL;DR: Presents theory, sources, and applications of stochastic differential equations of Ito's type; those containing white noise; and the role of partial differential equations in this context.