In this paper we employ renormalized viscosity and thermal diffusivity to construct a subgrid-scale model for large eddy simulation (LES) of turbulent thermal convection. For LES, we add νrenâΠu1/3(π/Δ)-4/3 to the kinematic viscosity; here Πu is the turbulent kinetic energy flux, and Δ is the grid spacing. We take subgrid thermal diffusivity to be same as the subgrid kinematic viscosity. We performed LES of turbulent thermal convection on a 1283 grid and compare the results with those obtained from direct numerical simulation (DNS) on a 5123 grid. We started the DNS with random initial condition and forked a LES simulation using the large wave number modes of DNS initial condition. Though the Nusselt number is overestimated in LES as compared to that in DNS, there is a good agreement between the LES and DNS results on the evolution of kinetic energy and entropy, spectra and fluxes of velocity and temperature fields, and the isosurfaces of temperature.
Vashishtha, S., Verma, M. K., & Samuel, R. (2018). Large-eddy simulations of turbulent thermal convection using renormalized viscosity and thermal diffusivity. Physical Review E, 98(4). doi:10.1103/physreve.98.043109
We thank Fahad Anwer, Abhishek Kumar, Anando Chatterjee, Shashwat Bhattacharya, Manohar Sharma, and Mohammad Anas for useful discussions. We are grateful to the anonymous referees for their insightful comments. The simulations were performed on the HPC system and Chaos cluster of IIT Kanpur, India, and the Shaheen supercomputer at King Abdullah University of Science and Technology (KAUST), Saudi Arabia. This work was supported by research grants PLANEX/PHY/2015239 from the Indian Space Research Organisation (ISRO), India, and project K1052 by KAUST.