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Airflows inside passenger cars and implications for airborne disease transmission

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Science Advances  01 Jan 2021:
Vol. 7, no. 1, eabe0166
DOI: 10.1126/sciadv.abe0166
  • Fig. 1 Schematic of the model car geometry, with identifiers the FL, RL, FR, and RR windows.

    The two regions colored in black represent the faces of the driver and the passenger. Table on the right summarizes the six configurations simulated, with various combinations of fully open and closed windows.

  • Fig. 2 Pressure distributions around the exterior of the car associated with a vehicle speed of 22 m/s (50 mph).

    (A) Surface pressure distribution. (B) Pressure distribution in the air at the midplane. The color bar shows the gauge pressure in pascals and emphasizes the midrange of pressures: [−180, 60] Pa. At this speed, the full range of gauge pressure on the surface is [−361, 301] Pa.

  • Fig. 3 Streamlines computed for the case in which the RL and FR windows are open.

    The streamlines were initiated at the RL window opening. The streamline color indicates the flow velocity. Insets show the FR and RL windows colored by the normal velocity. The RL window has a strong inflow (positive) of ambient air, concentrated at its rear, whereas the FR window predominantly shows an outward flow (negative) to the ambient.

  • Fig. 4 Air change rate (or ACH) calculated on the basis of a residence time analysis for different configurations.

    Here, the air change rate is given by 1/τr, where τr is the residence time in hours. Uncertainty estimate is based on the turbulence level.

  • Fig. 5 Driver-to-passenger transmission.

    (A) Schematic of the vehicle with a cut plane passing through the center of the inner compartment on which the subsequent concentration fields are shown. (B) The bar graph shows the mass fraction of air reaching the passenger that originates from the driver. (C) Heatmaps showing the concentration field of the species originating from the driver for different window cases. Note that the line segment A–D is at the front of the car cabin, and the flow direction in C is from left to right. Dashed lines represent open windows, and solid lines indicate closed windows. Here, C0 is the initial mass fraction of passive scalar at the location of the injection, where C/C0 = 1. Error bars in (B) are 1 SD of the concentration field around the passenger.

  • Fig. 6 Passenger-to-driver transmission.

    (A) Schematic of the vehicle with a cut plane passing through the center of the inner compartment on which the subsequent concentration fields are shown. (B) The bar graph shows the mass fraction of air reaching the driver that originates from the passenger. (C) Heatmaps showing the concentration field of the species originating from the passenger for different window configurations. Dashed lines represent open windows, and solid lines indicate closed windows. Here, C0 is the initial mass fraction of passive scalar at the location of the injection, where C/C0 = 1. Error bars in (B) are 1 SD of the concentration field around the driver.

Supplementary Materials

  • Supplementary Materials

    Airflows inside passenger cars and implications for airborne disease transmission

    Varghese Mathai, Asimanshu Das, Jeffrey A. Bailey, and Kenneth Breuer

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    • Figs. S1 to S7

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