This project has initiated studies that will reveal fundamental understanding of dispersed multiphase flows. Qualitative causal relationships between flow structures and droplets/bubbles have been revealed in the initial phase of the project. Results from these studies have been presented at two international conferences. The results constitute three papers (Taylor four-roll mill problem, 2D turbulence, and bubble buoyancy) that are in draft and will be submitted to scientific journals.
The initial phase of the project has further developed numerical methods for detailed simulations of disperse multiphase flow and also phase transition in dispersed multiphase flows. Two of the studies are under review for publication in scientific journals, and one work is in progress for submission to a scientific journal. The work on numerical further developments has been presented at two international conferences.
Numerical simulation results have been generated and will be analyzed to reveal the relationship between phase transition and flow structures. The project has succeeded in studying the relationship between fluid structures and mass transfer for bubbles rising in a liquid. The study is now being extended to realize this in turbulent flow.
The ultimate goal of the project is to use the new knowledge to propose a completely new basis for next-generation models for drop/bubble breakup and mass transport across phase boundaries.
The work on the numerical study has also established collaboration with other research groups and resulted in co-authorships.
The complexity of the studies in this project makes data-driven methods highly relevant. Data-driven methods have been applied and analyzed to study bubble dynamics, and the work is under consideration for publication in a scientific article and has been presented at an international conference. The project is now in a new phase where we will look at machine learning to understand the relationship between breakup and flow properties. This is work that has established a large network of collaboration.
Two articles are under review in scientific journals where fundamental studies have been carried out for turbulent flow, including those related to objectivity of turbulence.
Project meetings have been arranged with international collaborators.
Turbulence plays an enormous importance in many industrial applications. In industries concerned with dispersed drops-in-liquid or bubble-in-liquid flow, the drops/bubbles may fragment (the breakup phenomenon), merge (the coalescence phenomenon), or undergo phase transition (the interface mass transfer phenomenon). The available (CFD) models for these phenomena share the common feature that they are based on simplistic hypothesis for how turbulence interacts with the drop/bubble interface. The absent understanding of the mechanisms of turbulence-interface interactions constitutes a bottleneck for developing predictive models. Our underdeveloped understanding of these mechanisms has remained since the first proposed models; thus, constituting a nearly half-century-old problem. With the significant development of numerical methods and computational capacities in recent years, this model problem can finally be addressed. This project will break with the old traditions, and approaches the modelling of turbulence in interface mass transfer, breakup, and coalescence from a wholly new direction. For the first time the underlying mechanisms for turbulence-interface interactions will be uncovered. This will be a breakthrough in our physical understanding and allow a new theoretical foundation for developing the models for interface mass transfer, breakup, and coalescence without today's gross limitation. The ultimate results from this project is to establish the next-generation framework for modellers and users of CFD who are concerned with turbulent dispersed flow. This project certainly addresses a hard problem and its realization requires an interdisciplinary approach. It has thus been a great emphasis on international collaboration to enable the ambiguous scientific advancements of the project.
