Application of computer fluid dynamics CFD in livestock and poultry houses

In recent years, the application of computational fluid dynamics (CFD) in the simulation of environmental distribution in livestock and poultry houses has become more and more common. CFD technology is an effective and feasible method, which can make us more intuitive to see the change of air flow in the house. Sourabh et al. conducted a digital study on the airflow in the hen house, aiming at the comparison of two ventilation system schemes in the hen house and the transmission characteristics of epidemic diseases. In this paper, the CFD simulation method was used to analyze the airflow inside and outside the house, in which the transmission of virus particles was simplified to assume that it was a tracer gas (NH3), and the influence of heat plume generated by chickens in the laying house was also considered. By comparing two ventilation systems with opposite airflow directions, the results show that the bottom-up ventilation system is better than the top-down ventilation system. Daniella et al. evaluated an existing mechanically ventilated chicken coop and used CFD technology to analyze the location and number of exhaust fans in the ventilation system. In addition, Blanes, Lnbok L, Kwon, etc. all used CFD technology to evaluate the ventilation system in the chicken house, and carried out simulation research on the airflow distribution. Li Wenliang et al. used CFD technology to simulate and analyze the effects of the installation height, opening Angle and inlet wind speed of the rectangular air inlet damper on the air distribution in the closed flat chicken house. The results showed that the opening Angle of the air inlet varied with the installation height of the air inlet, and the resulting jet width varied to some extent. Zhai Yaofang et al. used numerical simulation method to study the airflow organization and heat and humidity environment in the closed cage laying hens' house. Here, he simplified the single row cage frame and its chicken body into cuboids with the same resistance characteristics in different directions, and set them as a porous medium model. Wang Xiaoshuai et al. used CFD technology to evaluate and analyze the thermal environment quality of the laying house, and carried out structural optimization design of the laying house. In the study, the author explained in detail the numerical simulation problems of the laying house, including modeling, grid division, boundary condition determination, etc. The research results provided an effective analysis method for the thermal environment simulation of livestock and poultry houses. It also provides theoretical basis and guidance for the rational design of ventilation system and cooling system of livestock and poultry houses.

Similarly, CFD technology is becoming more and more mature for environmental research in pig houses and cattle houses. Bernardo et al. used CFD method to redesign and evaluate the ventilation system in a pig house, and verified it in field tests. He Cheng et al. took the pig house as the research object and based on the CFD method, carried out the environmental numerical simulation of the air flow field and the temperature field in the house respectively, which provided the theoretical basis for the design of China's pig farm. Deng Shuhui et al. carried out CFD simulation on the air flow field and temperature and humidity field of the low roof transverse ventilated cattle barn, proposed the optimal design method of the LPVC cattle barn environment and carried out the empirical study, which provided the theoretical basis and technical support for the transformation and environmental control of LPCV cattle barn in China. Therefore, the application of CFD technology in the analysis of livestock and poultry houses is becoming more and more common.

To sum up, the environment of the pig house is becoming more and more complex, and the environmental control has been paid more and more attention, and environmental control has become an important part of large-scale breeding production technology. Numerical simulation based on computational fluid dynamics (CFD) is an important method to study the built environment. Because it can obtain the environmental distribution of air flow field, temperature field and pressure field in the three-dimensional space of building facilities, and the simulation results can be visualized, compared with other research methods, CFD simulation has the advantages of intuitive, low cost and short time. Therefore, it is more and more widely used in civil and agricultural buildings.