A strategy for modifying the effect of turbulence integral scale on fluctuating pressures of rectangular prisms

Abstract

The turbulence integral scale has a significant effect on the fluctuating pressures encountered by prisms. At present, the turbulence integral scale cannot be adequately simulated, leading to errors in the fluctuating pressure. Based on the two-wavenumber aerodynamic admittance function of fluctuating pressure, this paper describes a strategy for modifying the fluctuating pressure of rectangular prisms in turbulent flows. Using the three-dimensional theory of lift, a three-dimensional model of fluctuating pressure is established, in which the two-wavenumber power spectrum of fluctuating pressure is the product of the two-wavenumber coherence and the one-wavenumber power spectrum of fluctuating pressure, and is also the product of the two-wavenumber aerodynamic admittance function and the two-wavenumber power spectrum of oncoming velocity. An empirical form of the-wavenumber coherence of fluctuating pressure is derived, allowing the two-wavenumber power spectrum of fluctuating pressure to be calculated, and the two-wavenumber aerodynamic admittance function of fluctuating pressure to be obtained. The two-wavenumber aerodynamic admittance function of fluctuating pressure on a given body is almost independent of the turbulence, indicating that only one test is needed to modify the simulated error of fluctuating pressure. Finally, the results for a prism with a 1:3 side-ratio show that the simulated error of fluctuating pressure can be ignored when the simulated turbulence integral scale is 0.5 or 1.1 times the target value, and the simulated error is reduced from 24% to around 10% when the simulated turbulence integral scale is 0.25 times the target value.