We investigate the anisotropy in turbulent convection in a three-dimensional (3D) box using direct numerical simulation. We compute the anisotropic parameter A = u2⊥/(2u2), where u⊥ and u are the components of velocity perpendicular and parallel to the buoyancy direction, the shell and ring spectra, and shell-to-shell energy transfers. We observe that the flow is nearly isotropic for the Prandtl number Pr ≈ 1, but the anisotropy increases with the Prandtl number. For Pr = ∞,A ≈ 0.3, anisotropy is not very significant even inmextreme cases. We also observe that u feeds energy to u⊥ via pressure. The computation of shell-to-shell energy transfers reveals that the energy transfer in turbulent convection is local and forward, similar to hydrodynamic turbulence. These results are consistent with the Kolmogorov’s spectrum observed by Kumar et al. [Phys. Rev. E 90, 023016 (2014)] for turbulent convection
|Original language||English (US)|
|Journal||Physical Review Fluids|
|State||Published - Oct 28 2016|
Bibliographical noteKAUST Repository Item: Exported on 2021-04-02
Acknowledgements: We thank Biplab Dutta, Sandeep Reddy, Rohit Kumar, Anando Chatterjee, and J. K. Bhattacharjee for useful discussions and help in postprocessing. This work was supported by research grants from Indo-French Centre for the Promotion of Advanced Research (Grant No. SPO/IFCPAR/PHY) and Science and Engineering Research Board, India (Grant No. SERB/F/3279). Our numerical simulations were performed on HPC cluster of IIT Kanpur, Param Yuva, at the Centre for Development of Advanced Computing (CDAC), and Shaheen supercomputer at KAUST Supercomputing Laboratory, Saudi Arabia.
This publication acknowledges KAUST support, but has no KAUST affiliated authors.