Tiziano Tirabassi

Analytical Model for Air Pollution in the Atmospheric Boundary Layer

The worldwide concern due to the increasing frequency of ecological disasters on our planet urged the scientific community to take action. One of the possible measures are analytical descriptions of pollution related phenomena, or simulations by effective and operational models with quantitative predictive power. The atmosphere is considered the principal vehicle by which pollutant materials are dispersed in the environment, that are either released from the productive and private sector or eventually in accidental events and thus may result in contamination of plants, animals and humans. Therefore, the evaluation of airborne material transport in the Atmospheric Boundary Layer (ABL) is one of the requirements for maintenance, protection and recovery of the ecological system. In order to analyse the consequences of pollutant discharge, atmospheric dispersion models are of need, which have to be tuned using specific meteorological parameters and conditions for the considered region. Moreover, they shall be subject to the local orography and shall supply with realistic information concerning environmental consequences and further help reduce impact from potential accidents such as fire events and others. Moreover, case studies by model simulations may be used to establish limits for the escape of pollutant material from specific sites into the atmosphere.

Modelo matemático de dispersão de poluentes na atmosfera: um instrumento técnico para a gestão ambiental

The mathematical models of pollutant dispersion in the atmosphere represent an important technical instrument, as for the knowledge of the state of the atmosphere, united to the monitoring net, as for the environmental administration. In this work the operational and theoretical characteristics of air pollution models are evidenced. Models of new generation that can represent the atmospheric turbulence directly through the value of the Monin-Obukhov length and of the friction velocity are introduced. Besides, it is pointed out that a correct use of the transport and diffusion models in the atmosphere depends of a study about their capacities of representing real situations confronting the calculated values of the models with experimental observations. It is deepened in matter, seen the great present time of the phenomenon, the use of the mathematical models of dispersion in the management of the air quality in urban environment.

Meteorologia e poluição atmosférica

Neste trabalho apresentam-se os principais aspectos relacionados a meteorologia ligada ao processo de dispersao turbulenta de poluentes atmosfericos. Ressalta-se que a meteorologia desempenha um papel fundamental para o controle da qualidade do ar, pois os eventos meteorologicos guiam a dispersao de poluentes e sua deposicao no solo. Discutem-se os recentes melhoramentos da descricao e previsao dos fenomenos que envolvem a poluicao atmosferica considerando a melhoria da qualidade de vida da populacao.

Evaluation Of Mixing Height Over ComplexCoastal Terrain

The mixing height is one of the fundamental parameters to characterise its structure and is required in dispersion models. This paper is concerned with the evaluation of the hmix in a coastal area (Esino Valley) by a semi-empirical estimates of boundary layer parameters like the Monin-Obukhov length L and the roughness length ZQ. A preliminary evaluation of the methodology is presented.

A SIMPLE FORMULA FOR THE EVALUATION OF VALUE AND POSITION OF GROUND LEVEL CONCENTRATION FROM A POINT SOURCE

After setting realistic scenarios of the wind and diffusivity parameterizations the Ground Level Concentration is worked out by an analytical solution of the advection-diffusion equation, then an explicit approximate expression is provided for it allowing a simple expression for the position and value of the maximum.

Modelagem da Dispersão de Poluentes na Atmosfera Considerando uma Fonte Móvel

O presente trabalho refere-se ao problema de dispersao de poluentes na atmosfera com a emissao realizada atraves de uma fonte movel. Para representar este fenomeno, apresenta-se um novo modelo matematico que utiliza a equacao da adveccao-difusao. Resolve-se esta equacao atraves do metodo GILTT (Generalized Integral Laplace Transform Technique) e utiliza-se o experimento de OLAD (Over-Land Atmospheric Dispersion) para simulacao. Os resultados obtidos ressaltam a capacidade do modelo em representar o comportamento da dispersao presente no experimento.

A Model for Turbulent Diffusion in a Vertically Inhomogeneous Atmospheric Boundary Layer

An analytical solution of the one-dimensional turbulent diffusion equation considering nonFickian closure in a vertically inhomogeneous atmospheric boundary layer (ABL) is presented. The presented solution is improved and more physically consistent in the description of dispersion because it includes (for the first time) the explicit gravitational settling ( s w ) of large particles. Moreover, deposition velocity ( d v ) as a boundary condition, vertical turbulent velocity ( w  ), skewness ( k S ), vertical Lagrangian time ( w L T ) scale and relaxation time ( ) fi ite-velocity diffusio are i cluded. Via numerical simulations, we analyzed the influence of the countergradient term, dry deposition to the ground and gravitational settling on the concentration field. Our results demonstrate an example of the usefulness of analytical solutions to the advection-diffusion equation.An analytical solution of the one-dimensional turbulent diffusion equation considering non-Fickian closure in a vertically inhomogeneous atmospheric boundary layer (ABL) is presented. The presented solution is improved and more physically consistent in the description of dispersion because it includes (for the first time) the explicit gravitational settling ( ) of large particles. Moreover, deposition velocity ( ) as a boundary condition, vertical turbulent velocity ( ), skewness ( ), vertical Lagrangian time ( ) scale and relaxation time ( ) (“finite-velocity” diffusion) are included. Via numerical simulations, we analyzed the influence of the countergradient term, dry deposition to the ground and gravitational settling on the concentration field. Our results demonstrate an example of the usefulness of analytical solutions to the advection-diffusion equation. DOI: 10.5935/1984-6835.20160087

INFLUENCE OF SETTLING VELOCITY OF PARTICULATE MATTER ON GROUND LEVEL CONCENTRATIONS

The settling velocity and deposition of particulate matter on the earths surface has been introduced in an analytical solution of advection-diffusion equation. The influence of particle diameters in ground level concentration distribution was investigated in function of different atmospheric stability condiyions

A Closed Form Solution for Pollutant Dispersion Simulation in Atmosphere Under Low Wind Conditions

The present study proposes a mathematical model for dispersion of contaminants in low winds that takes into account the along-wind diffusion. The solution of the advection-diffusion equation for these conditions is obtained applying the 3D-GILTT method. Numerical results and comparison with experimental data are presented.

An Analytical Model for Contaminant Dispersion Release in the Atmospheric Boundary Layer Considering Time Variable Eddy Diffusivity

In this work we present a new model and simulations for more realistic scenarios incorporating in the diffusive model the dependence of the eddy diffusivity profile on the temporal variable. Numerical results and comparison with experimental data are presented.