Droplet deformation and heat transfer in isotropic turbulence

QS 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 droplet undergoing phase change in isotropic turbulence using numerical simulations with a hybrid lattice Boltzmann scheme. We solve the momentum and energy transport equations, where phase separation is controlled by a non-ideal equation of state and density contrast is taken into consideration. Deformation is caused by pressure and shear stress at the droplet interface. The statistics of thermodynamic variables is quantified and averaged in terms of 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.Different modes of oscillation are clearly identified from the deformation power spectrum for low Taylor Reynolds number $Re_\lambda$, whereas nonlinearities are produced with the increase of $Re_\lambda$, as intermediate frequencies are seen to overlap. As an outcome a continuous spectrum is observed, which shows a decrease that scales as $\sim f^{-3}$.Correlations between the droplet Weber number, deformation parameter, fluctuations of the droplet volume and thermodynamic variables are also examined.

Do-Quang, MinhKTH,Fysiokemisk strömningsmekanik(Swepub:kth)u1lej4d1 (författare)
Hermanson, Jim C.University of Washington, USA (författare)
Amberg, GustavKTH,Fysiokemisk strömningsmekanik(Swepub:kth)u1fx2m3t (författare)
KTHFysiokemisk strömningsmekanik (creator_code:org_t)

Av författaren/redakt...: Albernaz, Daniel ...; Do-Quang, Minh; Hermanson, Jim C ...; Amberg, Gustav

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TEKNIK OCH TEKNOLOGIER: TEKNIK OCH TEKNO ...; och Maskinteknik; och Strömningsmekani ...

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