Direct numerical simulation of polydisperse droplet suspensions in inhomogeneous turbulence

Liquid–liquid extraction is a key process in the chemical industry and holds an important place in the study of chemical processes at IFPEN. The difference in scale between the smallest droplets and the column height can reach four to five orders of magnitude, making the design of such processes face an inherent multi-scale challenge linked to turbulent two-phase flows.
Current numerical models, based on Euler-Euler simulations with a population balance equation, struggle to accurately predict the droplet size distribution in the extraction column. Although these approaches are relatively mature from a numerical perspective, they require closure laws relevant to the systems considered. At the current state, the exchange terms between the two fluids, as well as the terms governing droplet size changes (coalescence and breakup), are not predictive with existing models.
This PhD project aims to improve the closure laws using direct simulations of droplet populations subjected to gravity and turbulence. The simulations will rely on the Basilisk solver with an original interface-capturing methodology that controls coalescence through multiple volume-fraction fields (multi-VOF) and a method for turbulence forcing. This strategy has already demonstrated its full potential by enabling, for the first time, the direct numerical simulation of monodisperse population of droplets in homogeneous turbulence.
The first step of the PhD aims at extending this methodology to more realistic cases including gravity and bidispersity. Then, a detailed analysis of the simulation results must lead to the development of new models for drag and coalescence frequency which account for the gravity effects and polydispersity. Finally, these models will be validated on industrial liquid–liquid extractor cases where simulations and experiments are available in our institute.

IFP Energies nouvelles is a French public-sector research, innovation and training center. Its mission is to develop efficient, economical, clean and sustainable technologies in the fields of energy, transport and the environment. For more information, see our WEB site. 
IFPEN offers a stimulating research environment, with access to first in class laboratory infrastructures and computing facilities. IFPEN offers competitive salary and benefits packages. All PhD students have access to dedicated seminars and training sessions. 
 

Academic requirements    University master’s degree in fluid mechanics/chemical processes
Language requirements    English level B2 (CECR)
Other requirements    Numerical methods, Linux programming, C, python