scholarly journals Airflow Characteristics Downwind a Naturally Ventilated Pig Building with a Roofed Outdoor Exercise Yard and Implications on Pollutant Distribution

2020 ◽  
Vol 10 (14) ◽  
pp. 4931
Author(s):  
Qianying Yi ◽  
David Janke ◽  
Lars Thormann ◽  
Guoqiang Zhang ◽  
Barbara Amon ◽  
...  
Keyword(s):  
Air Pollutants ◽  
Pollutant Dispersion ◽  
Air Pollutant ◽  
Emission Mitigation ◽  
Surrounding Environment ◽  
Air Pollutant Dispersion ◽  
Treatment Technologies ◽  
Downwind Side ◽  
Pollutant Distribution ◽  
Wake Zone

The application of naturally ventilated pig buildings (NVPBs) with outdoor exercise yards is on the rise mainly due to animal welfare considerations, while the issue of emissions from the buildings to the surrounding environment is important. Since air pollutants are mainly transported by airflow, the knowledge on the airflow characteristics downwind the building is required. The objective of this research was to investigate airflow properties downwind of a NVPB with a roofed outdoor exercise yard for roof slopes of 5°, 15°, and 25°. Air velocities downwind a 1:50 scaled NVPB model were measured using a Laser Doppler Anemometer in a large boundary layer wind tunnel. A region with reduced mean air velocities was found along the downwind side of the building with a distance up to 0.5 m (i.e., 3.8 times building height), in which the emission concentration might be high. Additional air pollutant treatment technologies applied in this region might contribute to emission mitigation effectively. Furthermore, a wake zone with air recirculation was observed in this area. A smaller roof slope (i.e., 5° slope) resulted in a higher and shorter wake zone and thus a shorter air pollutant dispersion distance.

scholarly journals Airflow Characteristics Downwind a Naturally Ventilated Pig Building with a Roofed Outdoor Exercise Yard and Implications on Pollutant Distribution

2020 ◽  
Author(s):  
Qianying Yi ◽  
David Janke ◽  
Lars Thormann ◽  
Guoqiang Zhang ◽  
Barbara Amon ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Air Pollutants ◽  
Pollutant Dispersion ◽  
Laser Doppler Anemometer ◽  
Air Pollutant ◽  
Surrounding Environment ◽  
Air Pollutant Dispersion ◽  
Downwind Side ◽  
Pollutant Distribution ◽  
Wake Zone

The application of naturally ventilated pig buildings (NVPBs) with outdoor exercise yards is on the rise mainly due to animal welfare considerations, while the issue of emissions from the buildings to the surrounding environment is important. Since air pollutants are mainly transported by airflow, the knowledge on the airflow characteristics downwind the building is required. The objective of this research was to investigate airflow properties downwind of a NVPB with a roofed outdoor exercise yard for roof slopes of 5°, 15°, and 25°. Air velocities downwind a 1:50 scaled NVPB model were measured using a Laser Doppler Anemometer in a large boundary layer wind tunnel. A region with reduced mean air velocities was found along the downwind side of the building with a distance up to 0.5 m (i.e. 3.8 times building height), in which the emission concentration might be high. It was found that a smaller roof slope (i.e. 5° slope) resulted in a higher and shorter wake zone and thus a shorter air pollutant dispersion distance. It was concluded that a smaller roof slope could contribute to the dilution of air pollutants and a lower air pollutant concentration near the ground.

Air pollutant dispersion altered by urban-rural breeze and urban sprawl

2020 ◽  
Author(s):  
Yung-Chang Chen ◽  
Gong-Do Hwang ◽  
Wei-Nai Chen ◽  
C.-K. Charles Chou
Keyword(s):  
Large Eddy Simulation ◽  
Urban Sprawl ◽  
Air Pollutants ◽  
Pollutant Dispersion ◽  
Air Pollutant ◽  
Eddy Simulation ◽  
Synoptic Weather ◽  
Large Eddy ◽  
Air Pollutant Dispersion ◽  
Urban Rural

<p>Air pollution becomes a serious issue due to the population growing up and residential area sprawl in decades. Residential area is not only a major source of air pollutants but also an impact to generate an urban-rural thermal wind and to alter the dispersion of air pollutants. However, the urban-rural breeze caused by a metropolitan is not the only impact on the dispersion of air pollutants. Generally, a synoptic weather condition is the major impact to dominate how the air pollutant exactly diffuses. The most metropolitans are located in the coastal regions. Therefore, a naturally thermal wind, sea-land-breeze, plays also commonly an essential role to transfer the air pollutant. Additionally, topography and natural obstacle are unable to be ignored as an impact to obstruct flow streaming which brings the air pollutant away.</p><p>Overall, synoptic weather conditions, local sea-land-breeze patterns, and natural obstacles are three major natural impactors to influence air pollutant dispersion. The urban-rural-breeze pattern and the roughness of the urban area are regarded as the two anthropogenic factors to alter the large breeze system and thereby affecting the spreading pathway of the air pollutant. To analysis the interaction of above mentioned five impactors could be regarded as a comprehensive approach to consider how the air pollutant transfer from a metropolitan to air pollution suffering areas.</p><p>In this study, we apply either computational or measurement tools to consider the effects of metropolitan, Taichung, which is located in middle Taiwan, in the heat island effect and modification of the roughness to alter the natural breeze and also the dispersion of the air pollutant. Several intensive observation periods of 3-dimensional wind field network in boundary layer have been proposed as the evidences to discuss the impacts of urban sprawl on the breeze circulation in Taichung. Otherwise, a large-eddy-simulation model, Parallel-Large-Eddy-Simulation Model (PALM) is applied in the study initially to realize the influence of synoptic weather conditions and topography on air pollutant dispersion. Thereafter, the impacts of the heat fluxes and the roughness changing due to the urban sprawl are proposed in the study. Overall, the altering of metropolitan on the natural breeze is a slight but significant impact and could change the air pollutant dispersion.</p><p> </p><p>Key Words: Boundary Layer, Wind field, Large-Eddy-Simulation, PALM, Urban Sprawl, Heat Island Effect, Thermal Wind</p>

Case Study of Nanjing Inner Ring on Air Pollution Dispersion from Roadway Tunnel Portals

2012 ◽  
Vol 610-613 ◽  
pp. 1895-1900 ◽  
Author(s):  
Shu Jiang Miao ◽  
Da Fang Fu
Keyword(s):  
Air Pollution ◽  
Pollutant Dispersion ◽  
Air Pollutant ◽  
Urban Traffic ◽  
Lagrangian Model ◽  
Pollution Dispersion ◽  
Piecewise Function ◽  
Air Pollutant Dispersion ◽  
Air Pollution Dispersion

The tunnel module of a rather simple Lagrangian model GRAL (Grazer Langrange model) has been chosen to study air pollutant dispersion around tunnel portals in Nanjing inner ring. Two points have been made to popularize GRAL3.5TM (the tunnel module of a Lagrangian model GRAL; the update was in May 2003) and assure it more suitable for the actual situations in Nanjing. One is to derive a piecewise function of the intermediate parameter ‘stiffness’. Another is to take Romberg NOx-NO2 scheme into account. After these 2 works on GRAL3.5TM, NO2 dispersion from portals of all the 6 tunnels in Nanjing inner ring has been simulated. The importance of limiting urban traffic volume to control air quality around tunnel portals and roadways has been emphasized.

scholarly journals Estimation of the spatial distribution of maximum PM10 and PM2.5 concentration in Bandung City and surrounding countries using WRF-Chem Model (case study in July and October 2018)

2021 ◽  
Vol 893 (1) ◽  
pp. 012044
Author(s):  
H Salsabila ◽  
A Turyanti ◽  
DE Nuryanto
Keyword(s):  
Pollutant Dispersion ◽  
Meteorological Factor ◽  
Air Pollutant ◽  
Pollutant Concentration ◽  
Pollutant Emission ◽  
Dispersion Pattern ◽  
Model Case ◽  
The Public ◽  
Pollutant Distribution

Abstract Bandung is one of big cities in Indonesia with high activities on industrial and transportation that will increase the air pollutant emission and causes adversely affect the public health. Based on that matter, monitoring of air pollutant concentration is urgently needed to predict the direction of pollutant dispersion and to analyze which locations are vulnerable to maximum exposure of the pollutant. Field monitoring of air pollutant concentration needs much time and high cost, but modeling could help for this. One of the models that can be used to predict the direction of pollutant distribution is the Weather Research Forecasting/Chemistry (WRF-Chem) model, which is a model that combines meteorological models with air quality models. The output of the WRF-Chem running model on July and October 2018, which has been analyzed visually, showed the dispersion pattern of PM10 and PM2.5 is spread mostly to the west, northwest, and north following the wind direction. According to the output of the WRF-Chem model, Bandung Kulon is the most polluted subdistrict by PM10 and PM2.5 with an exposure frequency of 22 hours (PM10), 24 hours (PM2.5) on July 2018 and 19 Hours (PM10), 14 hours (PM2.5) on October 2018. The correlation value for meteorological parameters is quite high in July 2018 (R = 0.9 for wind speed and R = 0.82 for air temperature). So based on the meteorological factor, WRF-Chem model can be used to predict the direction of pollutant distribution.

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