Multiphase transport processes
Professor Omar Matar, Theme Lead
“We cover a number of challenges that society faces and being able to tackle those involves understanding fluid flows and making accurate measurements and predictions.”
Multiphase Transport Processes addresses problems across varying scales by understanding the behaviour of fluids in application areas which include energy, manufacturing, healthcare and the environment.
Researchers focusing on multiphase transport flows will tackle some of society’s greatest issues in areas such as energy, manufacturing and healthcare.
Examples include the breakup of fluid jets, the motion of liquid droplets over solid walls and liquid films in chemical reactors, condensers and separators, the trapping of supercritical carbon dioxide in subsurface rocks, to flow regime transitions in pipeline transportation, in-body flows within tissue, the circulatory system and the GI tract, complex fluid behaviour in manufacturing plants, and radiative thermal hydraulics in nuclear reactors.
The extremely complex nature of multiphase flows means they are often hard to predict and to probe experimentally which can be problematic as small changes to flows on a molecular level could create large-scale impacts.
The Multiphase Transport Flows research theme aims to address these issues by understanding more about how fluids of varying properties behave.
Through multidisciplinary research, using theoretical, experimental, and numerical simulations, researchers use their understanding of these systems to propose solutions to problems of central importance in industrial, environmental, and biomedical applications.
The theme focuses on pure and applied multi-disciplinary research, using theory, experiment, and numerical simulations, covering the areas of multiphase, multi-component fluid mechanics, reactive, non-isothermal flows, flows through porous media, and complex fluids.
Our work includes state-of-the-art laser-based methods for high spatio-temporal diagnostics as well as non-invasive imaging techniques such as X-ray Computed Tomography and Positron Emission Tomography. This means that we can probe transient and localised phenomena that are “buried” within opaque media, and to relate the behaviour of fluids to the properties of the environment surrounding them.
Scale is an important element of the work in this theme, utilising multi-scale tools suitable for representing the relevant phenomena at various scales, including molecular scales and their integration within macroscale process simulation systems. Our research includes a combination of microscopy, microfluids and acoustic-fluidics, to provide precision dynamic measurements on the micro and nanoscale alongside laboratory-scale to mini-plant scale reactors ranging from structured packed beds to bubble slurry columns and algal bioreactors.
Research centres and programmes institutes associated with this theme include the PETRONAS Centre for Engineering of Multiphase Systems (PETCEMS), the UKRI-funded PREMIERE programme and the Shell Digital Rocks Lab.
Immersive VR teaching for Fluid Dynamics at Imperial College
Researchers at Imperial have developed virtual reality software for teaching fluid dynamics.
Molecular Fluid Dynamics
Molecules bouncing, jiggling, and flowing together.
Everything is made of molecules; and fluids are no exception. The motion of a fluid can be understood in terms of the collective motion of its molecules bouncing, jiggling, and flowing together. In this video, we take a look at the molecular origins of many well-known phenomena, including the flow of a fluid at the nano-scale, the collective motions which lead to turbulent-like structures, the formation of droplets, the impact of introducing chemicals like soap (a surfactant) and the molecular origins of bubbles in boiling phenomena.
3D DNS of spray formation with the Code BLUE
3D DNS of spray formation with the Code BLUE
Three dimensional direct numerical simulation liquid jet surrounded by a faster coaxial air flow using 2048 cores in an IBM BlueGene/Q machine.
Shaking drop DNS with BLUE
A vibrated drop constitutes a very rich physical system, blending both interfacial and volume phenom
A vibrated drop constitutes a very rich physical system, blending both interfacial and volume phenomena. A remarkable experimental study was performed by M. Costalonga (PhD. Université Paris Diderot, 2015) highlighting sessile drop motion subject to horizontal, vertical and oblique vibration. Several intriguing phenomena are observed such as drop walking and rapid droplet ejection. We perform three-dimensional direct numerical simulations of vibrating sessile drops where the phenomena described above are computed using the massively parallel multiphase code BLUE. The fluid interface solver is based on a parallel implementation of a hybrid Front Tracking/Level Set method designed to handle highly deforming interfaces with complex topology changes. We developed parallel GMRES and multigrid iterative solvers suited to the linear systems arising from the implicit solution for the fluid velocities and pressure in the presence of strong density and viscosity discontinuities across fluid phases.
Drop breakup from a nozzle
Three-Dimensional Direct Numerical Simulation of Drop Coming out from a Nozzle.
3D DNS falling film annular flow Re~600
3D DNS falling film annular flow Re~600
PETRONAS Centre for Engineering of Multiphase Systems (PETCEMS)
PETRONAS are a progressive energy company that provides solutions and technologies for a sustainable future, with numerous multiphase projects.
Since their partnership began in 2013, PETRONAS have committed over £45 million to research at Imperial, with projects across the Department of Chemical Engineering, Department of Chemistry and the Department of Earth Science and Engineering.
The goal of the PETRONAS project is to address key challenges involving the engineering of multiphase systems in the energy industry. From these, PETRONAS can excel in their modelling and make their processes more efficient.
Their projects cover a range of themes across chemical engineering including the modelling of surfactants, CO2 absorption, carbonated rock failure and prediction and control of solids
Professor Omar Matar, Head of Chemical Engineering and Director of PETCEMS, said: “PETCEMS will address key challenges involving the engineering of multiphase systems in the energy industry, will generate impact on the industrial and academic communities globally, and will help accelerate the sector on the journey towards zero pollution.”
Securing greener and more advanced energy systems
In 2020, PETRONAS announced an ambition to reach net zero carbon emissions by 2050. The research conducted at Imperial will combine Imperial’s expertise in understanding and engineering the flow of solids, gases and liquid flows in multi-phase systems with advanced computational modelling, experiments and chemical synthesis allowing researchers to successfully extrapolate from lab conditions to the core complex conditions in the field.
One example project contributing to decarbonisation targets involves molecular modelling of surfactants - compounds that lower the surface tension of a substance to increase its spreadability.
Carbohydrate-based surfactants are currently under-developed surfactant class with potential applications in a diverse range of industrial scenarios including oil recovery, pharmaceuticals, personal care, household and industrial cleaning.
While natural oils and fats have long been employed as raw materials for the production of surfactants, the production of surfactants on a carbohydrate molecule has only recently become possible on a large industrial scale.
The resulting sugar-surfactants can be cost-effective as compared to the more ‘classical’ surfactants and are bio-sourced, meaning they are more sustainable and non-toxic, and can be appropriately tailored by modifying their morphology.
Experimental screening of surfactants is costly and slow due to the very large number of possible morphologies, and the need to chemically synthesize prototypes.
The molecular modelling project aims to use molecular simulations to calculate the surface tension of different surfactant structures in mixtures of water and oil.
All these structures are based on the alkyl polyglucoside surfactant, which is formed by a hydrophilic head (that has a glucoside ring) and a hydrophobic tail (that is a hydrocarbon chain). Molecular simulations are virtual experiments, so they can be used to design and identify key features for real experimental setups.
The results from these projects will be ideally suited for guiding the synthesis and ultimate field implementation of these surfactants.