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Velocity (arrows) and spanwise vorticity (colours) fields illustrating the passage of the cylinder with speed U * = 0.42, experiment EPIV2, through the air curtain. Figures (a) and (b) demonstrate the distortion of the curtain as the cylinder approaches, and figures (c) and (d) show the flow after the cylinder has passed through the doorway. The black space represents the area where the light is blocked by the cylinder base. The non-dimensional times are (a) t * = t/t f w = −0.69 and (b) t * = t/t f w = −0.58. (c) t * = t/t f w = 0.62 and (d) t * = t/t f w = 0.87. We set the time t = 0 as the time when the cylinder passes the jet axis. The dimensionless spanwise vorticity ωH/w m is shown beside figure (b) and the representative length of the velocity vector w/w m is marked beside figure (a).

Velocity (arrows) and spanwise vorticity (colours) fields illustrating the passage of the cylinder with speed U * = 0.42, experiment EPIV2, through the air curtain. Figures (a) and (b) demonstrate the distortion of the curtain as the cylinder approaches, and figures (c) and (d) show the flow after the cylinder has passed through the doorway. The black space represents the area where the light is blocked by the cylinder base. The non-dimensional times are (a) t * = t/t f w = −0.69 and (b) t * = t/t f w = −0.58. (c) t * = t/t f w = 0.62 and (d) t * = t/t f w = 0.87. We set the time t = 0 as the time when the cylinder passes the jet axis. The dimensionless spanwise vorticity ωH/w m is shown beside figure (b) and the representative length of the velocity vector w/w m is marked beside figure (a).

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Figure 2: Schematic showing the experimental setup. Experiments were...
Figure 3: (a) The non-dimensional transported volume˜Vvolume˜ volume˜V...
Figure 4: The effectiveness curve E c (D m,c ) of the air curtain,...
Figure 7: Velocity (arrows) and spanwise vorticity (colours) fields...
Contaminant transport by human passage through an air curtain separating two sections of a corridor: Part I -- uniform ambient temperature
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  • Sep 2020
Air curtains are commonly used as separation barriers to reduce exchange flows through an open-door of a building.Here, we investigated the effectiveness of an air curtain to prevent the transport of contaminants by a person walking along a corridor from a dirty zone into a clean zone. We conducted small-scale waterbath experiments with freshwater,...
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Context 1
... flow was illuminated with a light sheet that passed through the channel base and some of the light sheet was blocked by the cylinder base. In figure 7, this region is blacked out and the cylinder is marked by horizontal lines. The velocity vectors (u, w) in the x − z-plane are represented by arrows, and the spanwise component of vorticity ω y = w x − u z is represented by colours. ...
Context 2
... the present case, the curtain was naturally turbulent ( figure 6(b)) and, when the cylinder was sufficiently far away from the jet, shear layer eddies were visible on both sides of the jet. As the cylinder approached the air curtain ( figure 7(a)), the streamwise velocity induced by the cylinder pushes the jet forward. This is in line with our definition of D m,c in equation (11) cylinder was closer to the air curtain ( figure 7(b)), the central core of the jet was highly perturbed and the shear layer near the cylinder was suppressed. ...
Context 3
... the cylinder approached the air curtain ( figure 7(a)), the streamwise velocity induced by the cylinder pushes the jet forward. This is in line with our definition of D m,c in equation (11) cylinder was closer to the air curtain ( figure 7(b)), the central core of the jet was highly perturbed and the shear layer near the cylinder was suppressed. The air curtain was completely disrupted when the cylinder was underneath it. ...
Context 4
... air curtain was completely disrupted when the cylinder was underneath it. After the cylinder passage, the air curtain started to re-establish but the wake velocity continued to pull it towards the cylinder ( figure 7(c)). The jet trajectory in figures 7(c) and (d) is shown by the white dotted line. ...
Context 5
... can been seen in figure 9 the flux˜qflux˜ flux˜q ac /(lU c ) first increases after t * ∼ −1 due to the dynamic pressure of the cylinder (marked as (a) on the figure) as also seen in PIV image in figures 7 (a) and (b). In the time period (b) of figure 9, we observe that the flux increases after the passage of the cylinder caused by the transport in the cylinder wake, which is also seen in figure 7 (c). Finally, the flux decreases during period (c), due to the re-establishment of the air curtain as can be observed in figure 7(d). ...
Context 6
... the time period (b) of figure 9, we observe that the flux increases after the passage of the cylinder caused by the transport in the cylinder wake, which is also seen in figure 7 (c). Finally, the flux decreases during period (c), due to the re-establishment of the air curtain as can be observed in figure 7(d). ...
Context 7
... flow was illuminated with a light sheet that passed through the channel base and some of the light sheet was blocked by the cylinder base. In figure 7, this region is blacked out and the cylinder is marked by horizontal lines. The velocity vectors (u, w) in the x − z-plane are represented by arrows, and the spanwise component of vorticity ω y = w x − u z is represented by colours. ...
Context 8
... the present case, the curtain was naturally turbulent ( figure 6(b)) and, when the cylinder was sufficiently far away from the jet, shear layer eddies were visible on both sides of the jet. As the cylinder approached the air curtain ( figure 7(a)), the streamwise velocity induced by the cylinder pushes the jet forward. This is in line with our definition of D m,c in equation (11) cylinder was closer to the air curtain ( figure 7(b)), the central core of the jet was highly perturbed and the shear layer near the cylinder was suppressed. ...
Context 9
... the cylinder approached the air curtain ( figure 7(a)), the streamwise velocity induced by the cylinder pushes the jet forward. This is in line with our definition of D m,c in equation (11) cylinder was closer to the air curtain ( figure 7(b)), the central core of the jet was highly perturbed and the shear layer near the cylinder was suppressed. The air curtain was completely disrupted when the cylinder was underneath it. ...
Context 10
... air curtain was completely disrupted when the cylinder was underneath it. After the cylinder passage, the air curtain started to re-establish but the wake velocity continued to pull it towards the cylinder ( figure 7(c)). The jet trajectory in figures 7(c) and (d) is shown by the white dotted line. ...
Context 11
... can been seen in figure 9 the flux˜qflux˜ flux˜q ac /(lU c ) first increases after t * ∼ −1 due to the dynamic pressure of the cylinder (marked as (a) on the figure) as also seen in PIV image in figures 7 (a) and (b). In the time period (b) of figure 9, we observe that the flux increases after the passage of the cylinder caused by the transport in the cylinder wake, which is also seen in figure 7 (c). Finally, the flux decreases during period (c), due to the re-establishment of the air curtain as can be observed in figure 7(d). ...
Context 12
... the time period (b) of figure 9, we observe that the flux increases after the passage of the cylinder caused by the transport in the cylinder wake, which is also seen in figure 7 (c). Finally, the flux decreases during period (c), due to the re-establishment of the air curtain as can be observed in figure 7(d). ...