Dissertation Defence: Aerosol Flow Dynamics for Mitigating Airborne Disease Transmission Indoors
April 1 at 9:30 am - 1:30 pm
Mojtaba Zabihi, supervised by Dr. Sunny Li, will defend their dissertation titled “Aerosol Flow Dynamics for Mitigating Airborne Disease Transmission Indoors” in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Mechanical Engineering.
An abstract for Mojtaba Zabihi’s dissertation is included below.
Examinations are open to all members of the campus community as well as the general public. Registration is not required for in-person exams.
ABSTRACT
This dissertation focuses on mitigating airborne disease transmission through two primary strategies: (1) assessing the impact of large-scale indoor airflow patterns and (2) implementing localized airflow control to remove respiratory particles before their dispersion. The investigation into large-scale flow patterns was conducted numerically using a classroom model based on an actual university classroom at the University of British Columbia. A ventilation strategy design that prioritizes airborne infectious disease mitigation in university classrooms, UFAD-CDR, is proposed. This design reduced airborne particle concentrations by 85% compared to baseline ventilation. Additionally, a new parameter, Horizontality, is introduced to characterize large-scale flow patterns, highlighting their impact and suggesting modifications to ventilation standard codes to account for these effects. The effectiveness of localized airflow control was examined in a consultation room through the implementation of an innovative personalized ventilation system based on the push-and-pull concept. This system enhances indoor air quality while maintaining occupant comfort. The efficacy of this novel aerosol removal device was compared to conventional PV systems, with results demonstrating a significant reduction in infection probability when using the new device. To ensure accuracy in capturing indoor particle dispersion, a fully transient Eulerian-Lagrangian approach was employed. This method utilizes Unsteady Reynolds-Averaged Navier-Stokes (URANS) turbulence models coupled with unsteady tracking of discrete particles using a stochastic method to simulate particle dispersion. This approach enables the simulation of individual particle trajectories as both the background flow and particles evolve in time and space. Additionally, in-house experiments on indoor particle spread were conducted to generate low-concentration aerosols that could be replicated numerically, and the resulting data were used to validate the numerical model.
