The outbreak of COVID-19 pandemic in the beginning of 2020 has made it necessary
to review many practices in countless areas, changing our lifestyles
drastically. Humanity has put health issues in priority to deal with the disease
effectively. While health systems are having difficult times in terms of patient
care, vaccination, and treatment protocols, existing designs in many areas have
proven to be inefficient in preventing or decelerating the pandemic. As the
disease is transmitted mainly by particle transfer through coughing, sneezing,
and even with speaking, wearing face masks and keeping a distance of 2 m as well
as hygiene (especially hand) are shown to be effective methods. However, long
exposure to indoor air populated with people is still a major risk due to the
possibility of high concentration of virus-contaminated air. Ventilation systems
in general must be redesigned, not only in terms of filtering capabilities, but
reestablishing the air streams taking place during the ventilation as well. In
modern buses as well as passenger aircrafts, ventilation air is blown from a
narrow outlet/diffuser to guarantee a laminar flow for passenger comfort. The
air is then returned to the central ventilation system through a large grille
that is mostly located in the rear part of the bus. The objective of this
numerical study is to visualize the air streams within a bus due to ventilation.
Examining the flow visualization shows that the exhaled air from the infected
passengers in the front seats can easily be conveyed along the bus, making it
possible to be inhaled by healthy persons in other seats, posing a high health
risk. Therefore, it is suggested that the air not be returned to the central
ventilation system through a rear grille, but instead longitudinal grilles
parallel to supply outlets providing a stream perpendicular to longitudinal axis
of bus, thus reducing the risk of contaminated air being inhaled by other
passengers.
