Jibola Obafemi Owolabi disputerer for ph.d.-graden i ingeniørvitenskap / Jibola Obafemi Owolabi will defend his thesis for the PhD degree in Engineering Science
Jibola Obafemi Owolabi disputerer for ph.d.-graden i ingeniørvitenskap og vil offentlig forsvare avhandlingen / Jibola Obafemi Owolabi will defend his thesis for the PhD degree in Engineering Science:
“CFD Modelling of the Multiphase Dynamics of Respiratory Bioaerosols in Confined Environments: Turbulence, Evaporation, and Humidity Interactions”.
Avhandlingen er tilgjengelig her / The doctoral thesis is available here.
Auditoriet er åpent for publikum. Disputasen vil også bli strømmet. Opptak av disputasen vil være tilgjengelig i en måned. / The auditorium is open to the public. The defense will be streamed. A recording of the defense will be available for one month.
Prøveforelesningen starter kl. 10:15 / The trial lecture starts at 10:15. Tittel:
“Emerging Low-Cost Sensors for Indoor Environmental Quality Measuring Several Parameters: Reliability, Opportunities, and the Future of Ventilation”.
Disputasen starter kl. 12:15 / The defense starts at 12:15.
Prøveforelesning strømmes her, disputas strømmes her / The trial lecture will be streamed here, and defense will be streamed here.
Sammendrag av avhandlingen / Summary of the thesis:
Airborne transmission of respiratory pathogens in indoor environments demands high-fidelity CFD models that resolve both unsteady jet dynamics and composition-dependent aerosol microphysics. This thesis develops and validates such a framework, addressing longstanding gaps in turbulence closure selection and in assumptions about pure water droplets, as exposed by the SARS-COV-2, COVID-19 pandemic.
Through systematic benchmarking, unsteady RANS (URANS) turbulence models, Standard ( 𝑘 – 𝜖), 𝑅𝑁𝐺 (𝑘−𝜖), 𝑅𝑒𝑎𝑙𝑖𝑧𝑎𝑏𝑙𝑒 (𝑘−𝜖), and 𝑆𝑆𝑇 (𝑘−𝜔) were evaluated against time-resolved PIV for cough and sinusoidal breathing jets. Standard (𝑘 – 𝜖) was excluded due to systematic underprediction of expulsion plume penetration. Among the remaining closures, 𝑅𝑒𝑎𝑙𝑖𝑧𝑎𝑏𝑙𝑒 (𝑘−𝜖) underperformed, 𝑅𝑁𝐺 (𝑘−𝜖) excelled in transitional and fully developed/far-field regimes, while 𝑆𝑆𝑇 (𝑘−𝜔) dominated near-field shear. Phase-resolved centreline decay was validated across near- (1<𝑥/𝑑<2.2), transitional- (2.2<𝑥/𝑑<5.6), and fully developed/far-field (𝑥/𝑑>5.6) regimes (𝑅2>0.92), yielding region-specific semi-empirical surrogates 𝑈/𝑈0=𝐾(𝑥/𝑑)−𝑛 for reduced-order risk models.
Furthermore, a novel κ–Köhler-consistent, solute-conserving Eulerian–Lagrangian solver was integrated into OpenFOAM to resolve transient evaporation of salt–protein droplets across a range of indoor RH (20−60%). Composition sensitivity peaks non-monotonically at 37−70% RH for micrometre-scale droplets, where salt-rich deep-lung emissions persist 45% longer than protein-rich nasal droplets, invalidating pure-water approximations in typical occupied spaces.
The open-source solver framework unifies validated URANS flows with microphysics, enabling parametric assessment of ventilation, layout, and RH control. Intermediate humidity maximizes both droplet persistence and pathogen viability, amplifying risk; extremes offer dual protection. This physics-grounded tool advances from particle-count proxies to spatially resolved exposure prediction, informing precision ventilation design and source-specific intervention strategies.
Hovedveileder / Main supervisor:
As. Professor Amar Aganovic, Department of Automation and Process Engineering, Faculty of Engineering Science and Technology, UiT The Arctic University of Norway.
Biveiledere / Co-supervisors:
Bedømmelseskomité / Evaluation committee:
Prøveforelesning og disputas ledes av as. professor Eivind Brodal / The trial lecture and defense are led by As. Professor Eivind Brodal.
De som ønsker å opponere ex auditorio kan sende e-post til Eivind Brodal / Opponents ex auditorio should contact Eivind Brodal.