Effects of turbulence integral scales on characteristics of fluctuating wind pressures

Abstract

To investigate the effects of turbulence integral scale, four rectangular models were tested in grid-generated turbulent flows, and the characteristics of fluctuating pressures on windward surfaces were obtained. The results show that all statistical parameters except the mean pressures depend on both the longitudinal integral scale (Lux) and depth (D) of the model. The root-mean-square (rms) values of the fluctuating pressure coefficients and their correlation as well as the spanwise coherence increase with the turbulence integral scale. As the integral scale decreases, the power spectra of the fluctuating pressures in the low-frequency region, which are controlled by the quasi-steady effect, remain almost unchanged, whereas those in the high-frequency region attenuate more rapidly. To seek a potential modification method for correcting the error margin caused by an imprecisely simulated turbulence integral scale, an empirical model of aerodynamic admittance function (AAF) of fluctuating pressure was proposed with consideration of Lux /D as a key variable. Finally, using the fluctuating pressure on the model with a side ratio of 1:3 as an example, the error margins of the fluctuating pressures were discussed. It was discovered that the maximum deviation of the rms value of the fluctuating pressure coefficient reached approximately 25% when the simulated turbulence integral scale was one-sixth the target value.