Dr Bruño Fraga MSc, PhD, HEA

Dr Bruño Fraga

Department of Civil Engineering
Associate Professor
Civil Engineering Admissions

Contact details

Telephone
+44 (0) 121 414 4212
Email
b.fraga@bham.ac.uk
View my research portal
Address
Room 222
School of Engineering
University of Birmingham
Edgbaston
Birmingham
B15 2TT
UK

Bruño Fraga specialises in developing Computational Fluid Dynamics (CFD) models to enhance our understanding of turbulent and multiphase flows, driving innovative applications in these areas. His current focus includes indoor air quality, airborne pathogen transport, bubble/particle-induced turbulence and water treatment.

Qualifications

  • Visiting Scholar, Georgia Tech
  • Visiting Scholar, Stanford University
  • Post-Graduate Certificate in Higher Education, University of Birmingham
  • Assistant Professor, University of Birmingham
  • Research Associate, Cardiff University
  • PhD in Civil Engineering, A Coruña University
  • Visiting Researcher, Chalmers University
  • MSc in Applied Mathematics and Numerical Simulation, A Coruña University
  • MEng in Environmental Engineering, Santiago de Compostela University

Biography

DNS of bubble swarm

Dr Fraga gained an MEng on Environmental Engineering by the University of Santiago de Compostela (Spain) with 1st class honours and a National Outstanding Graduate Prize. He then proceeded to undertake a MSc in Applied Math and Numerical Simulation moved by his interest in mathematical modelling. After this he pursued further specialisation in Fluids modelling, and he enrolled in a PhD programme in Civil Engineering that he completed at the universities of A Coruña (Spain) and Chalmers (Sweden), on the topic of turbulence modelling for open-channel flows. Bruño moved to the UK in 2013 to progress his academic career as a postdoctoral fellow in Cardiff University, where he developed multi-parallel algorithms for Lagrangian Particle Tracking and Immersed Boundary Methods. In late 2017 he was awarded the position of Lecturer in Numerical Modelling at the University of Birmingham. He was invited and fully funded as visiting scholar at Stanford University in 2018 and Georgia Tech in 2024, to apply his models and algorithms on the topic of bubble-induced turbulence.

Bruño and his research group are the developers of the code Multiflow3D, which incorporates novel formulations of Eulerian-Lagrangian algorithms to solve particle-laden flows of very different nature with remarkable accuracy, from turbidity currents to microplastic pollution, wastewater treatment or virus-laden aerosols (for example: A LES-based Eulerian–Lagrangian approach to predict the dynamics of bubble plumes and Influence of thermal stratification on the transport of polydispersed expiratory particles). Dr Fraga’s research produced a breakthrough in our understanding of bubble-induced turbulence, earning him scholarship in the prestigious Center for Turbulence Research at Stanford University in 2018. His work demonstrated that the ‘turbulent signature’ of bubbly flows does not depend on deformability or coalescence in any significant manner (see The role of breakup and coalescence in fine-scale bubble-induced turbulence. I. Dynamics). As work-package lead in Met Office-funded Indoor Air Quality Emissions & Modelling System (IAQ-EMS, led by CP) project (£1m), Bruño is developing the Chem-LES model, bringing together high-resolution fluid dynamics and explicit chemical reactions in indoor settings. As lead of UKRI-funded Fusion Forest (£1m), he will co-develop a model to predict the spread of fungal pathogens in treescapes. He also leads BuildAir (£120k), a network aimed to incorporate airborne infection risk in the built environment.

Bruño has also participated in knowledge transfer projects with researchers from Brazil and Turkey, sponsored by British Council. These were focused on water and wastewater treatment. He has working collaborations with the private sector, including Deltares Institute or Severn Trent, on matters such as novel methods for wastewater treatment and prevention of salt intrusion in freshwater systems. Dr Fraga currently co-leads the Fluids Research Group at the School of Engineering and the Water Technology stream at the University of Birmingham’s Water Centre. Bruño is a In2ScienceUK volunteer.

Teaching

  • Bruño is module leader on 2nd year Open Channel Flow Hydraulics and also teaches Fluid Mechanics and Energy Transfer. He supervises graduate and postgraduate projects and was MSc convenor for Civil Engineering between 2018 and 2023.

Postgraduate supervision

Current students

  • Aleksandra Monka
  • Riza Siregar
  • Yu Zhang
  • Fuad Alqrinawi (2nd supervisor)
  • Zijian Chen (2nd supervisor)
  • Niloofar Mohammadzadeh (2nd supervisor)
  • Faisi Ikhwali (2nd supervisor)

Graduated students

  • Boyang Chen (2022)

Research

 

Bruño and his group aim to apply their modelling expertise to real life problems to overcome societal and environmental challenges. These are some of the overarching topics leading his research:

Fluid Dynamics of Infection Risk

Humans spend approximately 90% of their time in indoor settings hence indoor air quality (IAQ) is of critical importance for overall exposure to air pollution and hence public health. The COVID-19 pandemic highlighted the importance of IAQ and airborne expiratory particles (aerosols) on the exposure to and transmission of respiratory. Experts in the field call for a paradigm shift, comparable to the collective public health transformation in water sanitation or food quality and safety standards during the XIX and XX centuries, respectively. Bruño has three active projects on this topic: Fusion Forest (Lead, £1m, UKRI), IAQ-EMS (Co-Lead, £1m, Met Office) and BuildAir (Lead, £120k, UKRI).

Bruño is leading the modelling part within the Indoor Air Quality Emissions Modelling System project funded by Met Office. His postdoctoral student Zhen Liu are jontly simulating pollutant emissions and ventilation in indoor environments. This project will generate two modelling outputs: a specialist model that will be adopted by Met Office as their main indoor air quality assessment tool and a more user-friendly reduced order model. The former output, labelled Chem-LES will be built on top of my code Multiflow3D by coupling the fluids solver with a chemical model framework.

Bruño's  student Aleksandra Monka have collaboratively developed the first algorithm capable of reproducing the dispersion of expiratory pathogen-laden particles, that range from the size of droplets to aerosols in a common framework. During an expiratory event, a multiphase (gas and liquid particles) buoyant turbulent cloud is released in which particles of various sizes are suspended. These expiratory particles exhibit different physical behaviour based on their size; larger particles are mostly unaffected by the cloud, while smaller particles remain suspended within it for long periods of time and follow air.

Large-eddy simulation of expiratory particles transport with Multiflow3DLarge-eddy simulation of expiratory particles
transport with Multiflow3D.

Particle-Laden Flows

The presence of a dispersed phase within a fluid matrix exhibits unique behaviours and new challenges for modellers and experimentalists. Particle-laden flows are ubiquitous in nature and engineering applications, from micro-plastic pollution and sediments in rivers to pollen and seeds transported by wind, droplets and aerosols spread by  the occupants of a room or gas bubbles and oil droplets released during a deep-sea oil spill. His group has developed a significant body of work in this area. They have developed a four-way coupled Eulerian-Lagrangian CFD-DEM model that they are currently applying to microplastic pollution (with my students Fuad Alqrinawi and Zijien Chen) and turbidity currents (with Boyang Chen).

Bubble-induced Turbulence

This is a fundamental topic that complements the more applied areas of my work. Engineering practice has embraced CFD to address multiphase flow scenarios, yet vast discrepancies have been reported when calculating flow properties using turbulence models specifically designed for bubble-induced turbulence. This is a problem I encountered during my career. In 2015 I developed an Eulerian-Lagrangian algorithm to solve gas/oil plumes and found that it could provide excellent results in terms of liquid velocities and plume development, but failed when estimating the turbulent kinetic energy. In 2018, during my time as a visiting scholar in Stanford, I investigated how multiphase turbulence is significantly different than its single-phase counterpart, and that we still lack fundamental insight on its mechanisms. 

Bruño has been since working in collaboration with researchers in Stanford University, Georgia Tech and Newcastle University in gaining further understanding on the nature of multiphase turbulence. They recently made a breakthrough by proving that bubble deformability does not explain in any significant manner the signature of multiphase turbulence. All results point at wake-to-wake interaction as the main mechanism of turbulence modulation. This peculiar signature, once believed to only occur in bubbly flows, is present wherever there is a dispersed phase and the Reynolds number is sufficiently high. This has relevant repercussions, from applications to particle-laden flows to the study of the energy transfer in a wind farm, where wakes from different generators interact with each other.

Direct numerical simulation of inertial particles of various sizes falling in a liquid matrix with Multiflow3D.Direct numerical simulation of inertial particles of
various sizes falling in a liquid matrix with Multiflow3D.

Publications

Selected Publications

View all publications in research portal

Expertise

See Bruno's YouTube Channel.