This paper studies the spatial concentration distribution and temporal evolution of exhaled and sneezed/coughed droplets within the range of 1.0 to 10.0 μm in an office room with three air distribution methods,includ...This paper studies the spatial concentration distribution and temporal evolution of exhaled and sneezed/coughed droplets within the range of 1.0 to 10.0 μm in an office room with three air distribution methods,including mixing ventilation（MV）,displacement ventilation（DV）,and under-floor air distribution（UFAD）.The simulation results indicate that exhaled droplets with diameters up to 10.0 μm from normal respiration process are uniformly distributed in MV.However,they become trapped at the breathing height by thermal stratifications in DV and UFAD,resulting in a high droplet concentration and an increased exposure risk to other occupants.Sneezed/coughed droplets are more slowly diluted in DV/UFAD than in MV.Low air speed in the breathing zone in DV/UFAD can lead to prolonged human exposure to droplets in the breathing zone.展开更多
A P-vector method was optimized using variational data assimilation technique, with which the vertical structures and seasonal variations of zonal velocities and transports were investigated. The results showed that w...A P-vector method was optimized using variational data assimilation technique, with which the vertical structures and seasonal variations of zonal velocities and transports were investigated. The results showed that westward and eastward flowes occur in the Luzon Strait in the same period in a year. However the net volume transport is westward. In the upper level (0m -500m),the westward flow exits in the middle and south of the Luzon Strait, and the eastward flow exits in the north. There are two centers of westward flow and one center of eastward flow. In the middle of the Luzon Strait, westward and eastward flowes appear alternately in vertical direction. The westward flow strengthens in winter and weakens in summer. The net volume transport is strong in winter (5.53 Sv) but weak in summer (0.29 Sv). Except in summer, the volume transport in the upper level accounts for more than half of the total volume transport (0m bottom). In summer, the net volume transport in the upper level is eastward (1.01 Sv), but westward underneath.展开更多
基金The National Natural Science Foundation of China(No.50808133)the Dean's Reserve of Faculty of Construction and Land Use at the Hong Kong Polytechnic University
文摘This paper studies the spatial concentration distribution and temporal evolution of exhaled and sneezed/coughed droplets within the range of 1.0 to 10.0 μm in an office room with three air distribution methods,including mixing ventilation（MV）,displacement ventilation（DV）,and under-floor air distribution（UFAD）.The simulation results indicate that exhaled droplets with diameters up to 10.0 μm from normal respiration process are uniformly distributed in MV.However,they become trapped at the breathing height by thermal stratifications in DV and UFAD,resulting in a high droplet concentration and an increased exposure risk to other occupants.Sneezed/coughed droplets are more slowly diluted in DV/UFAD than in MV.Low air speed in the breathing zone in DV/UFAD can lead to prolonged human exposure to droplets in the breathing zone.
基金Supported by the Major State Basic Research Program (No. G1999043810) Open Laboratory for Tropical Marine Environmental Dynamics (LED)+2 种基金 South China Sea Institute of Oceanology Chinese Academy of Sciences and the NSFC (No. 40306004).
文摘A P-vector method was optimized using variational data assimilation technique, with which the vertical structures and seasonal variations of zonal velocities and transports were investigated. The results showed that westward and eastward flowes occur in the Luzon Strait in the same period in a year. However the net volume transport is westward. In the upper level (0m -500m),the westward flow exits in the middle and south of the Luzon Strait, and the eastward flow exits in the north. There are two centers of westward flow and one center of eastward flow. In the middle of the Luzon Strait, westward and eastward flowes appear alternately in vertical direction. The westward flow strengthens in winter and weakens in summer. The net volume transport is strong in winter (5.53 Sv) but weak in summer (0.29 Sv). Except in summer, the volume transport in the upper level accounts for more than half of the total volume transport (0m bottom). In summer, the net volume transport in the upper level is eastward (1.01 Sv), but westward underneath.
