The effect of active grid initial conditions on high Reynolds number turbulence

Abstract

The most expansive active grid parametric study to date is conducted in order to ascertain the relative importance of the various grid parameters. It is identified that the three most important parameters are the Rossby number, Ro, the grid Reynolds number, \(Re_M,\) and the wing geometry. For \(Ro > 50\), an asymptotic state in turbulence intensity is reached where increasing Ro further does not change the turbulence intensity, while other parameters continue to vary. Three wing geometries are used: solid square wings, solid circular wings, and square wings with holes. It is shown that the wings with the greatest blockage produce the highest turbulence intensities and \(Re_\lambda\), but that parameters such as the Kolmogorov, Taylor, and integral scales are not significantly influenced by wing geometry. Finally, it is demonstrated that for several different sets of initial conditions that produce the same \(Re_\lambda\), the spectra are collapsed everywhere but at the largest scales when normalized by Kolmogorov variables. This result suggests that regardless of the very different origins of the turbulence, the shape of the spectra at high wavenumbers is dependent only on \(Re_\lambda\), hence demonstrating a degree of independence from the initial conditions

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