Droplet deformation and heat transfer in isotropic turbulence

Authors: Albernaz, D.L., Do-Quang, M., Hermanson , J., Amberg, G.A.
Document Type: Article
Pubstate: Submitted
Journal: Journal of Fluid Mechancis
Year: 2016


The heat and mass transfer of deformable droplets in turbulent flows is crucial to a wide range of applications, such as cloud dynamics and internal combustion engines. This study investigates a single droplet undergoing phase change in isotropic turbulence using numerical simulations with a hybrid lattice Boltzmann scheme. Phase separation is controlled by a non-ideal equation of state and density contrast is taken into consideration. Droplet deformation is caused by pressure and shear stress at the droplet interface. The statistics of thermodynamic variables are quantified and averaged over both the liquid and vapor phases. The occurrence of evaporation and condensation is correlated to temperature fluctuations, surface tension variation and turbulence intensity. The temporal spectra of droplet deformations are analyzed and related to the droplet surface area. Di fferent modes of oscillation are clearly identfi ed from the deformation power spectrum for low Taylor Reynolds number Re, whereas nonlinearities are produced with the increase of Re, as intermediate frequencies are seen to overlap. As an outcome a continuous spectrum is observed, which shows a decrease in the power spectrum that scales as  f^(-3). Correlations between the droplet Weber number, deformation parameter, fluctuations of the droplet volume and thermodynamic variables are also developed.