Modulation of fluid temperature fluctuations by particles in turbulence

Modulation of fluid temperature fluctuations by particles due to thermal interaction in homogeneous isotropic turbulence is considered. For simplicity, only thermal coupling between fluid and particle is considered, and momentum coupling is neglected. Application of the statistical theory in cloud turbulence study leads to the prediction that modulation of fluid temperature fluctuations by particles is described as a function of the Damkohler number, which is defined as the ratio of the turbulence large-eddy turnover time to the gas thermal relaxation time. Direct numerical simulations are conducted for two-way thermal coupling between fluid temperature field and point particles in homogeneous isotropic turbulence. The simulation results are shown to agree accurately with the theoretical prediction.