Numerical Investigation on the Sensitivity of Turbulence Statistics to Small Velocity Variations in Grid-Generated Turbulence based on k-ε model

抄録

The sensitivity of the turbulence statistics of grid-generated turbulence to small variations in the mean flow velocity was investigated in this study. Such small velocity variations negligibly affect the anisotropy of grid-generated turbulence. The relative effects of these small velocity variations on the turbulent kinetic energy, its dissipation, the length scales of the turbulence, the invariance of the turbulence, and the turbulent diffusion coefficient were examined. The k–ε turbulence model, which is a standard computational fluid dynamics model, was used to estimate the relative effects. The small variations in the mean flow velocity were produced by adjusting the wind tunnel ceiling height. The relative effects of these variations on the turbulence statistics were compared by the gradients in their respective linear approximations. The invariance of the homogeneous turbulence was found to be the most sensitive to small velocity variations, whereas the two length scales were relatively insensitive to the variations. The sensitivity of the turbulence statistics was assessed using linear approximations in this study.