A Comparative Study of Stationary and Non-stationary Wind Models Using Field Measurements

Abstract

We present a comparative study of the conventional stationary wind speed model and a newly proposed non-stationary wind speed model using field measurements. The concept of, and the differences between, the two wind models are briefly reviewed. Wind data recorded by a field measurement system for wind turbulence parameters (FMS-WTP) of 1-year duration are analyzed using the two wind models. Comparisons were made between the wind characteristics obtained from the two models, including hourly mean wind speed, turbulence intensity, the wind spectrum, integral length scale, root coherence function and probability density function. The effects of wind types (monsoon or typhoon), statistical properties (stationary or nonstationary), and surface roughness (open-sea fetch or overland fetch) on wind characteristics are discussed. The comparative study demonstrates that the non-stationary wind model appears to be more appropriate than the conventional stationary wind speed model for characterizing turbulent winds of one-hour duration over complex terrain.

Previsão do vento utilizando o modelo atmosférico WRF para o estado de Alagoas

“…Então, as séries da velocidade do vento registrada pelos anemômetros em Água Branca, Girau do Ponciano e Maragogi, ao atingirem elevadas intensidades, aumentarão os desvios nas comparações diretas com os prognósticos do modelo WRF. Além disto, Chen et al (2007) demonstram que confrontar a eficiência de modelos de mesoescala com dados observados em um ponto de grade implica em uma cadeia de limitações de exatidão numérica. Dentre elas, a comparação temporal sofre influência da frequência de registro digital das medições anemométricas, ocorrendo a cada 10 minutos, sendo diferente da escala temporal do WRF, que é horária.…”

Measurements and analysis of non-stationary wind characteristics at Sutong Bridge in Typhoon Damrey

“…3(a). As shown in the figure, for the Typhoon Damrey, the constant hourly mean wind speed U based on the traditional stationary wind speed model is 11.79 m/s, while the maximum, minimum and hourly averaged values of the time-varying mean wind speed are 13.60 m/s, 10.21 m/s and 11.70 m/s, respectively.It is noted that the hourly averaged value of the time-varying mean wind speed is very close to the corresponding constant hourly mean wind speed, which suggests application of the non-stationary wind speed model in practice(Chen et al 2007). Typical nonstationary lateral wind speed time histories and corresponding mean wind speed are presented inFig.…”

“…For non-stationary wind processes, the definition of statistical properties needs to be updated accordingly so that the time-varying mean values could be naturally integrated. A non-stationary wind speed model, in which the constant mean wind speed is replaced by the time-varying mean values, is an effective scheme for this purpose (Wang and Kareem 2004;Chen et al 2007;McCullough et al 2014).…”

Numerical and Experimental Investigation on Parameter Identification of Time‐Varying Dynamical System Using Hilbert Transform and Empirical Mode Decomposition

“…The author also has applied the HT+EMD approach for linear identification problems as parameters identification of structures with closed space modal properties [10], structural damage detection [11], and parameter identification of an existing longspan bridge [12]. We further demonstrated in Chen et al [13] that EMD is a very powerful tool in processing nonstationary signal which is frequently encountered in time-varying identification problem. Though successful in numerical examples, experimental verifications of the abovementioned techniques, especially for time-varying system, are still rare.…”