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Oscillating-grid turbulence influenced by secondary flows was experimentally investigated under various grid-oscillation conditions using two-dimensional particle image velocimetry (PIV). The secondar...y-flow fields were classified into three distinct patterns based on their spatial structures. The vertical profiles of horizontal and vertical turbulence intensities, turbulent kinetic energy, and energy dissipation rate were found to follow power-law scaling in a strongly turbulent region. These power-law scaling relations were quantitatively evaluated and compared with those in previous studies to clarify the influence of secondary flows on the vertical profiles. In the far-field region away from the grid, however, the turbulent fields deviated from the power-law scaling and instead showed more complex profiles depending on the secondary-flow structures. This change in behavior suggests that, in the far-field region, turbulence production and transport associated with large-scale secondary flows become important processes, leading to deviations from the diffusion-dissipation balance of oscillating-grid turbulence. Furthermore, analyses of the measured isotropy ratio and horizontal homogeneity of the turbulent field indicated that the isotropy ratio was particularly sensitive to the secondary-flow structures. These findings underscore the importance of explicitly accounting for secondary-flow effects in understanding the structure of oscillating-grid turbulence and in developing its parameterizations.show more
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p1145-1158