Cristian Constante Amores
Project title: Multi-phase Modelling of Oil-Water Droplet Size Distributions
Supervisor: Professor Omar K. Matar
The aim of the project is to develop capabilities for the simulation of an evolving droplet size distribution associated with the dynamics of a liquid-liquid interface undergoing breakup into droplets, which can then potentially coalesce. Both the spatio-temporal evolution of a jet issuing from a nozzle and two-phase annular flow will be considered as a representative exemplar flow that exhibits sufficient complexity so as to be practical relevance
Predicting multiphase flow dynamics is complicated by the multi-scale nature of the flow, and the tremendously complex interfacial topology. The position of the interface must be also determined as part of the solution, which adds to the simulation complexity. Interface-tracking and Interface-capturing methods are the two different approaches to resolve the position of the interface.
Direct numerical simulations (DNS) with interface-tracking or interface-capturing capabilities can, in principle, resolve all the relevant length- and time-scales in the flow; for highly turbulent flows (Re ~ 104-105), this is computationally highly expensive with current methods even for single-phase flows. Unlike single-phase DNS, additional length scales need to be resolved which may be similar to the Kolmogorov length scale, related to, for instance, the smallest droplets sheared from a film or a jet, events controlled by capillary forces.
Blue is the numerical solver chosen for the research. It is a new solver for massively-parallelised simulations of fully three-dimensional multiphase flows. The solver runs on a variety of computer architectures, from laptops to supercomputers, and, so far, on 131072 threads or more (limited only by the availability to us of more threads). The code uses a domain- decomposition strategy for parallelization with MPI. The fluid interface solver is based on a parallel implementation of the LCRM hybrid front tracking/level set method, designed to handle highly deforming interfaces with complex
We have also access to a large amount of experimental data on annular flows generated by former students and postdocs of the group through the Transient Multiphase Flows Consortium on two phase annular flow. This experimental data needs to be post-process and will be used to validate the numerical predictions provided by Blue
Shin, S., Chergui, J., Kahouadji, L., Juric, D., Matar, O. and Craster, R. (2017). An Interface-Tracking Technique for Multiphase Flow with Soluble Surfactant. Computational Physics.
Shin, S., Chergui, J. and Juric, D. (2017). A solver for massively parallel direct numerical simulation of three-dimensional multiphase flows. Journal of Mechanical Science and Technology, 31(4), pp.1739-1751.
Tryggvason, G., Scardovelli, R. and Zaleski, S. (2011). Direct numerical simulations of gas-liquid multiphase flows. Cambridge: Cambridge University Press.
Tryggvason, G., Bunner, B., Esmaeeli, A., Juric, D., Al-Rawahi, N., Tauber, W., Han, J., Nas, S. and Jan, Y. (2001). A Front-Tracking Method for the Computations of Multiphase Flow. Journal of Computational Physics, 169(2), pp.708-759