Effect of the Reynolds number on turbulence kinetic energy exchanges in flows with highly variable fluid properties
Abstract
Spatial and spectral energy exchanges associated with the turbulence kinetic energy per unit mass, or the halftrace of the velocity covariance tensor, are studied in an anisothermal low Mach number turbulent channel flow. The temperatures of the two channel walls are 293 K and 586 K. This generates a strong temperature gradient in the wallnormal direction. The effect of the temperature gradient on the energy exchanges is investigated using two direct numerical simulations of the channel, at the mean friction Reynolds numbers 180 and 395. The temperature gradient creates an asymmetry between the energy exchanges at the hot and cold sides due to the variations of the local fluid properties and low Reynolds number effects. The low Reynolds number effects are smaller at higher Reynolds numbers, reducing the asymmetry between the hot and cold sides. We also decomposed the energy exchanges in order to study separately the meanproperty terms, as found in the constantproperty isothermal case, and the thermal terms, specific to flows with variable fluid properties. The significant thermal terms have a similar effect on the flow. Besides, low Reynolds number effects have a negligible impact on thermal terms and only affect meanproperty terms.
 Publication:

Physics of Fluids
 Pub Date:
 January 2019
 DOI:
 10.1063/1.5080769
 arXiv:
 arXiv:2006.04438
 Bibcode:
 2019PhFl...31a5104D
 Keywords:

 Physics  Fluid Dynamics
 EPrint:
 Physics of Fluids, American Institute of Physics, 2019, 31 (1), pp.015104