The simulation of large-sized pathogen-laden respiratory droplet spread inside a passenger ferry

• CFD simulations reveal droplet spread patterns in ferry passenger cabins. • CFD simulations reveal droplet spread patterns in ferry passenger cabins. • Passenger position significantly affects droplet movement and infection risk. • A 1.5 m distancing rule is generally effective but may fail in some cases. • Most droplets deposit on seats and floors, highlighting cleaning importance. This paper presents computational fluid dynamics (CFD) of Reynolds-Averaged Navier Stokes (RANS) simulations to analyse the flow movement of pathogen-laden particles/droplets with relatively large diameter range of 50 − 150 μ m inside an air-conditioned ferry cabin. Three major cases are investigated, the first cases is when one infected passenger sits on a passenger chair that is located close to the edge of the cabin in the centre row; the second case is when the infected passenger is standing in the middle of the cabin; and the third case is for a passenger who sits on the opposite edge of the cabin, and located at the front row. For each of these three positions, three air conditioner velocities were investigated. The results indicate that as the air conditioner velocities velocity increases, the spread of the particles is also getting wider and they are elevated further from the floor. The simulation results also indicate that passenger location is also an important aspect in influencing the spread of the particles, particularly for those who are directly blown by the air conditioner’s airflow. Our results also show the effectiveness of 1.5-meter (minimum 1-meter) social distancing rule by the WHO (World Health Organisation) for particles with diameter range of 50 − 150 μ m, however there are certain cases in which this separation distance may be insufficient. Such as in which the infected patient is directly blown by the air conditioner or when the particle diameters are smaller than 50 μ m in which it could be suspended in the air longer. Finally, this report also discuss RANS validation technique with respect to experiment and the weakness of RANS in simulating the movement of particles inside a room. Hence the result of the simulation should be treated as an approximation only.