Review of Wind Tunnel Modelling of Flow and Pollutant Dispersion within and from Naturally Ventilated Livestock Buildings  
[PERSON]  
1 Czech Academy of Sciences, 182 00 Prague, Czech Republic; [EMAIL_ADDRESS] (Z.J. ); [EMAIL_ADDRESS] (M.J.)  
2 Department of Engineering for Livestock Management, Leibniz Institute for Agricultural Engineering and Bioconomy (AIP), Max-Eyth-Allee 100, 14469 Potsdam, Germany; [EMAIL_ADDRESS] (D.J. ); 2  
[PERSON]  
1 Czech Academy of Sciences, 182 00 Prague, Czech Republic; [EMAIL_ADDRESS] (Z.J. ); [EMAIL_ADDRESS] (M.J.)  
[PERSON]  
2 Department of Engineering for Livestock Management, Leibniz Institute for Agricultural Engineering and Bioconomy (AIP), Max-Eyth-Allee 100, 14469 Potsdam, Germany; [EMAIL_ADDRESS] (D.J. ); 2  
[PERSON]  
2 Department of Engineering for Livestock Management, Leibniz Institute for Agricultural Engineering and Bioconomy (AIP), Max-Eyth-Allee 100, 14469 Potsdam, Germany; [EMAIL_ADDRESS] (D.J. ); 2  
[PERSON]  
3 Wageningen Livestock Research, 6708 WD Wageningen, The Netherlands; [EMAIL_ADDRESS] 3  
[PERSON]  
4 Institute of Animal Science and Technology, Universitat Politecnica de Valencia, Camino de Vera s.n., 46022 Valencia, Spain; [EMAIL_ADDRESS]. sation from the manure surface) is driven by the local microenvironment conditions above the manure surface, such as the gaseous ammonia concentration, the mean air velocity, turbulence intensity, and air temperature. The properties of the manure (e.g., the concentration of urea, pH, and temperature) have a critical impact on the ammonia emission [4; 5]. According to the first [PERSON]'s law, the ammonia emission rate decreases with the increase of the ammonia concentration in the air or a decrease in the ammonia concentration in the manure. In contrast, previous studies on ammonia mass transfer above the emission surface have shown that the mean air velocity and turbulence [6; 7] and the temperature difference between the manure and the surrounding air increase the emission [8]; the higher the airflow and turbulence intensity above the manure surface, the higher the ammonia emission. In the case of air temperature, the temperature difference between the manure and the surrounding air is important: The higher the temperature difference, the higher the ammonia emission from the manure. Simple models have been developed to predict the ammonia emission from naturally ventilated livestock buildings (NVLBs) based, for example, on the outdoor temperature [9]. However, detailed information about the ammonia emission mechanisms is hidden by such models. The modelling of ammonia dispersion within and from NVLBs is more challenging than in cases of those buildings that are ventilated mechanically (e.g., piggery and poultry houses) [10; 11]. Compared to mechanically ventilated livestock buildings, NVLBs must have larger openings in order to provide enough clean air and remove excess heat. However, due to these large openings, the wind directly impacts the indoor environment of NVLBs. During the warm and transitional seasons, the openings of the NVLB represent more than 50-100% of the building wall area. Hence, the external flow sweeps with ease through the building and may increase ammonia emissions, due to the higher airspeed and turbulence intensity above the manure surface. Even during winter conditions, the openings are still large enough to allow interaction between the external flow and the indoor environment, which can produce complex turbulent flow patterns inside and around the building (see Figure 1). Owing to the diurnal weather cycles and surrounding topology, the wind is highly turbulent. The instantaneous intensity and direction of the wind measured at the building height rarely correlate with those of the flow measured at the building's openings. Even if the time is averaged over, for example, 30 min, better results may not be obtained, as the turbulent structures developed naturally in the incoming flow have a bigger time scale than these averages [12].