Silvana Maldaner

Derivation of third-order vertical velocity turbulence moment in the convective boundary layer from large eddy simulation data: an application to the dispersion modeling

A new formulation for the vertical turbulent velocity third statistical moment in a convective boundary layer is proposed. The parameterization is based directly on the definition of this higher order moment, with velocity skewness and variance being calculated from large eddy simulation data. The formulation, included in a Lagrangian stochastic dispersion model, has been tested and compared with expressions for the third moment obtained from experimental data and reported in the literature, using concentration data from field experiments. The application of a statistical evaluation shows that the proposed parameterization has one of the best overall adjustments to the data.

Testing Physical and Mathematical Criteria in a New Meandering Autocorrelation Function

An alternative formulation for the low wind speed-meandering autocorrelation function is presented. Employing distinct theoretical criteria, this mathematical formulation, from a physical point of view, is validated. This expression for the meandering autocorrelation function reproduces well-observed wind-meandering data measured in a micrometeorological site located in a pampa ecosystem area (South Brazil). The comparison shows that the alternative relation for the meandering autocorrelation function is suitable to provide meandering characteristic parameters. Employing MacLaurin’s series expansion of a lateral dispersion parameter that represents cases in which turbulence and oscillatory movements associated to the meandering events coexist, a new formulation for the turbulence/meandering dissipation rate has been presented.

Modelagem da Dispersão de Contaminantes em Condições Estáveis e de Vento Fraco

O presente trabalho tem como objetivo apresentar uma solucao analitica para a equacao de adveccao-difusao tridimensional em condicoes de vento fraco em uma camada limite estavel dominada por cisalhamento. O modelo inclui a difusao longitudinal que nao pode ser negligenciada sobre condicoes de vento fraco. A solucao da equacao de adveccao-difusao e obtida aplicando a tecnica da transformada integral. Para validar a presente metodologia, dados coletados durante o experimento classico Prairie Grass foram empregados. Para verificar o desempenho do modelo, neste trabalho foram utilizados coeficientes de difusao com formulacao integral e algebrica para parametrizar a turbulencia. O perfil do vento e descrito por uma lei de potencia e similaridade.

ESTIMATION OF WATER INFILTRATION IN A FLOODPLAIN SOIL THROUGH THE GREEN-AMPT MODEL WITH ADJUSTMENT PARAMETERS

The need to find a model that describes the process of water infiltration into the soil which could be more closer to the reality is extremely important, especially considering the physical characteristics of a soil has, because a better understanding of this process is of fundamental importance for the efficient management of soil and water in agricultural crops. This study aims to validate the model of Green-Ampt in a rice-growing area. The experiment was conducted in the experimental site of Paraiso do Sul - RS, where soil samples were collected for physical analysis and used the double ring infiltrometer to obtain the values of cumulative infiltration. The results obtained through the Green-Ampt model did not generate acceptable results for application. With the development of the work, it was concluded that for the implementation of Green-Ampt model it is necessary to find a new parameter setting proposal that can describe the process of infiltration to the soil type studied.

OBTAINING THE MEANDERING LOOP PARAMETER IN LOW WIND SPEED CONDITION

The looping parameter m is the main value to characterize the meandering phenomenon. This parameter is relationship with negative lobes in the observed autocorrelation function generated from components of horizontal speed. In this work, we present a study comparing the mean values of the looping parameter between 2 diverse sites in the Brazilian sector.

CLASSIC CALIBRATION EQUATIONS FOR LONG WAVE RADIATION IN THE PAMPA REGION ON A CLEAR DAY

The atmospheric longwave radiation is a fundamental quantity in calculating the radiation balance at the surface. Measures of this magnitude in the gaucho Pampas region are scarce. An alternative estimate for this variable is the use of classical equations that use air temperatures and steam pressure. The objective of this study was to evaluate the performance of five equations in the estimation of the long atmospheric wave radiation for a clear day on a Pampa biome located in Santa Maria-RS. Atmospheric longwave radiation measurements taken throughout the year 2014 on the site of Santa Maria / Brazil were used to validate the performance of equations. After the radiation estimates by classical equations, an adjustment by least squares was empegando to calibrate such equations to the biome Pampa. By adjusting it noted that the equation Brutsaert (1975) was best described obsevada long wave radiation in the PAMPA region.

UMA NOVA EXPRESSÃO PARA A VARIÂNCIA DA VELOCIDADE TURBULENTA CONVECTIVA DERIVADA DE UM MODELO LES

The aim of this study is to derive a new expression for the vertical turbulent velocity variance using LES data in a convective boundary layer.

LARGE-EDDY SIMULATION IN LOW WIND CONDITIONS

Os resultados preliminares de uma simulacao dos grandes turbilhoes (LES) em uma camada limite convectiva com vento fraco sao apresentados. Uma simulacao LES foi realizada incluindo, na superficie, a teoria de similaridade de Monin-Obukhov e a teoria de conveccao natural. Os resultados foram comparados com radiossondagens e observacoes superficiais realizadas no CNR (Italian National Research Council) de Torino (em 22 de setembro de 2007), Italia. O modelo LES mostrou-se capaz de descrever uma condicao atmosferica de baixa velocidade do vento.

DERIVAÇÃO DE PARÂMETROS DE DISPSERSÃO PARA UM MODELO GAUSSIANO NA CAMADA LIMITE CONVECTIVA

Neste trabalho, uma expressao para os parâmetros de dispersao vertical e lateral e obtida. Integram-se numericamente tais expressoes e verifica-se que estas possuem comportamento identico a uma expressao simples proposta por Degrazia et al. (1998). Emprega-se, entao, a expressao geral obtida para o parâmetro de dispersao lateral, em um modelo de dispersao gaussiano para simular a concentracao de contaminantes do experimento de difusao com tunel de vento de Poreh e Cermak (1984).

INVESTIGATION WITH LARGE-EDDY SIMULATION OF THE SEA BREEZE REGIMES

Neste trabalho, investigam-se as interacoes entre a brisa maritima e a turbulencia sobre a Terra empregando uma simulacao dos grandes turbilhoes (LES). Os resultados mostram que o modelo LES e capaz de similar um regime de brisa Mar-Terra-Mar.