Turbulence anisotropy with higher-order moments in flow through passive grid under rigid boundary influence

The investigation presents the estimate of the degree of deviation from the isotropic turbulence in terms of Reynolds stress tensor for grid generated turbulence under the influence of bottom boundary. The turbulence triangle, Eigen values, and the invariant functions are presented at near and far field regions of the grids with different solidity ratio. In addition, the work also deals with the analysis based on third-order moments of the velocity fluctuations and the ratio of momentum flux to the turbulent kinetic energy in the frequency domain. The Reynolds stress anisotropy exposes that the anisotropic invariant maps possess a closed looping trend in the near field region and an open looping trend in the far-field region of the grid. Further, to describe the physical behaviour of the velocity time-series of random fluctuating components in the stream-wise directions, the probability distribution function are estimated and interpreted.

Automated summary

This investigation presents an estimate of deviation from isotropic turbulence in grid-generated turbulence influenced by the bottom boundary. It analyzes the turbulence triangle, Eigen values, and invariant functions in near and far field regions with different solidity ratios, and examines the third-order moments of velocity fluctuations and the ratio of momentum flux to turbulent kinetic energy in the frequency domain. The study also reveals the anisotropy of Reynolds stress, showing a closed looping trend in the near field region and an open looping trend in the far-field region of the grid. Additionally, probability distribution functions are used to describe the physical behavior of velocity time-series of random fluctuating components in the stream-wise directions.