Analysis of droplet evaporation in isotropic turbulence through droplet-resolved DNS

Direct numerical simulations (DNS) of the evaporation of interface-resolved n-heptane fuel droplets in forced homogeneous isotropic turbulence (HIT) are performed at 10 bar and 348 K. A parametric study is conducted in which the ratio of initial droplet diameter to Kolmogorov lengthscale and the liquid volume fraction are varied in the ranges 0 < d(0)/eta <= 17 and 10(-4) <= alpha(l) <= 10(-2), respectively. The DNS results are validated against experimental data for an isolated droplet evaporating in HIT. Our results show that increasing the liquid volume fraction of droplets decreases the evaporation rate and causes the evaporation rate to deviate from the classical d(2)-law. Evaporation models based on the Frossling correlation are tested in an a priori study using the DNS results. It is shown that, in general, the Frossling correlation is inaccurate when predicting the droplet Sherwood number in turbulent conditions. Modeling aspects of the Spalding number in the context of multiple interacting droplets are discussed. (C) 2021 Elsevier Ltd. All rights reserved.