Transport and Removal of Expiratory Droplets in Hospital Ward Environment

Figures & data

FIG. 1 Schematic diagram of the ward setting.

FIG. 2 The distributions of mean velocity magnitudes obtained with different grid sizes.

FIG. 3 Number percentages of deposited droplets relative to the total injection number. Test case: 11.6 ACH, vertical injection.

TABLE 1 Boundary conditions and parameter inputs for the numerical simulations

Supply air conditions
Total airflow supply rates:    1060 m^3/hr (11.6 ACH)
550 m^3/hr (6.0 ACH)
Supply diffuser: four-way-spread-type, supply jets had an angle of 15° from ceiling
Turbulence intensity at supply outlet: 45% (obtained from PIV measurement)
Supply air temperature: 292.2 K (19.2°C)
Supply air water vapor mass fraction: 0.00963 (corresponded to 60% RH at 21.5 °C)
Thermal boundary conditions
Walls and bed surfaces: adiabatic	Heat box surfaces: constant heat flux (100 W each)
Thermal Manikin: constant heat flux (75 W each)
Boundary effects to aerosols
All solid surfaces: Trap	Supply inlet: Reflect	Exhaust outlet: Escape
Droplet generation properties
Air velocity at nozzle outlet: 10 m/s	Binary diffusivity of water vapor in air: 0.288 cm^2/s
Air temperature at nozzle outlet: 307 K	Volatile fraction: 0.94
Material: Water	Airflow rate: 0.4 L/S

FIG. 4a Airflow velocity vector plot at the middle plane (y = 0) during injection for the vertical (above) and lateral (below) injection cases (11.6 ACH).

FIG. 4b Airflow velocity vector plot at y = 1 m (above) and −2 m (below) 60 s after injection for the lateral injection cases (11.6 ACH).

FIG. 4c Airflow velocity vector field measured by PIV at locations marked in a) and b).

FIG. 5 Mean vertical positions of the vertical injection case.

FIG. 6 Mean vertical positions of the lateral injection case.

FIG. 7 Mean lateral dispersion distances in the x direction in the vertical injection case.

FIG. 8 Mean lateral dispersion distances in the x direction in the lateral injection case.

FIG. 9 Removal number fraction due to deposition in different simulation cases.

FIG. 10 Overall deposition velocities in different simulation cases.

FIG. 11 Deposition velocities of expiratory droplets with initial size = 1.5 μm (a); 12 μm (b); 28 μm (c); and 45 μm (d) for difference surfaces. (Continued)