Proposal of a new autocorrelation function in low wind speed conditions

Abstract

h i g h l i g h t s• We propose a new mathematical expression to describe the meandering phenomenon.• We employ wind data measured in a nocturnal PBL to obtain experimental ACF. • The new ACF satisfactorily represents the negative lobes of the meandering phenomenon. a b s t r a c tIn this study a new mathematical expression to describe the observed meandering autocorrelation functions in low-wind speed is proposed. The analysis utilizes a large number of best fit curves to show that the proposed theoretical function well reproduces the general form and the negative lobes characterizing the experimental meandering autocorrelation function. Further, the good agreement of the measured autocorrelation curves with the proposed algebraic autocorrelation function allows to calculate the magnitudes of the meandering period and of the loop parameter. The results agree with the values presented and discussed in the literature. Therefore, the new formulation describing experimental meandering autocorrelation functions can be used to simulate the dispersion of contaminant during low wind episodes and to determine relevant meandering parameters.

Identification and Estimation of the Period of Non Turbulent Oscillatory Processes in the Stable Boundary Layer Through Autocorrelation Functions

“…Isto pode estar relacionado com a natureza do fenômeno físico responsável pela ocorrência de meandro, todavia, uma investigação mais aprofundada é necessária para embasar tal informação. Moor et al (2015) tiveram um bom ajuste com a autocorrelação dos dados experimentais da componente zonal de velocidade do vento. Porém, para intervalos nos quais o período do meandro é pequeno e o parâmetro de meandro é alto, a função de autocorrelação de Moor et al (2015) apresentou melhor desempenho (Figura 2, painel inferior).…”

“…Com o objetivo de obter uma expressão que seja capaz de descrever a forma geral e os lobes negativos que caracterizam a autocorrelação de dados experimentais com meandro, Moor et al (2015) propôs uma nova função de autocorrelação (Equação (3)), que utiliza os mesmos parâmetros utilizados na Equação (2).…”

“…Posteriormente, as funções de autocorrelação propostas por Frenkiel (1953) e Moor et al (2015), foram ajustadas determinar os parâmetro m e T. Após a determinação destes dois parâmentros foi calculado o período da oscilação de meandro, pela seguinte equação :…”

Physical and Mechanical Characterization of Copaifera sp. Wood Specie

“…Thus, the horizontal wind meandering phenomenon is an important physical component that must be incorporated in air pollution models. These oscillations in the u and v horizontal wind components are practically independent of the atmospheric stability conditions, and are responsible for the presence of negative lobes in observed autocorrelation function (ACF) associated to the horizontal components of the wind vector ( [3], [4]). This meandering ACF oscillatory behaviour makes it very difficult to establish a mean wind direction.…”

Testing Physical and Mathematical Criteria in a New Meandering Autocorrelation Function

“…Recently, Moor et al [6] proposed to utilize a new mathematical formulation to fit the observed low wind speed-meandering autocorrelation functions. This functional form for the horizontal wind velocity components u and v may be written as follows:…”