Research On Motion Law Of Human Exhaled Aerosol Based On Large Eddy Simulation

In modern life,people spend most of their time indoors,so the quality of indoor air is directly related to people's health.How to design good indoor air distribution and effectively remove pollutants has been widely concerned by scholars at home and abroad.The spread of aerosols such as viruses and bacteria in indoor pollutants has brought serious harm to people.A large number of studies have shown that poor ventilation in confined Spaces increases the concentration of microbial aerosols and the risk of human infection.Therefore,it is very important to study the diffusion law of microbial aerosols in ventilated rooms.In this study,large eddy simulation(les)turbulence model was used to study the motion of aerosol particles generated by human respiration in different ventilation forms.Starting from the theory,the theoretical knowledge of large eddy simulation,discrete phase model and numerical solution of computational fluid dynamics is introduced.According to the literature research,the self-adaptive sublattice model of the wall is selected as the research method.The basic force of aerosol is introduced,and the force of aerosol produced by respiration is calculated and analyzed.An experimental platform was built to verify the accuracy of large eddy simulation turbulence model,and the results showed that the prediction results of large eddy simulation were good.Two factors affecting sinusoidal respiration and room temperature were simulated,and the importance of sinusoidal respiration and the necessity of considering different room temperature conditions were determined.Three ventilation forms,namely displacement ventilation,mixed ventilation and laminar ventilation,were simulated at three room temperatures and three ventilation speeds to study the diffusion of particulate matter generated by human respiration.Various operating conditions were evaluated and analyzed in terms of comfort,aerosol concentration distribution and aerosol removal efficiency.The results show that displacement ventilation has a better performance in terms of comfort.Even at a high wind speed,the airflow velocity around the human body is less than 0.4m/s.Only in the case of medium wind speed,the airflow velocity around the human body of mixed ventilation and displacement ventilation is less than 0.5m/s.In the case of high wind speed,both types of ventilation will cause high airflow velocity around the human body and lead to discomfort.Displacement ventilation in human breath area pollutant concentration is relatively low,especially in the chamber is 24? and 27?,the concentration of human activity area are under 1 e-11 kg/m3;The mixing degree of airflow in the mixed ventilation room is higher,so the indoor particle distribution is more uniform,especially when the wind speed is high,the aerosol concentration in the human activity area is all below le-12kg/m3.The air flow in the lower area of the laminar ventilation room is relatively disorderly,resulting in a high concentration of aerosol in its respiratory area under various conditions,and higher than 2e11kg/m3 in most working conditions.At room temperature for 24? high wind speed under the condition of displacement ventilation in the form of aerosol elimination efficiency as high as 1.98%;When the room temperature 30? under the condition of high wind speed mixing ventilation in the form of particulate matter elimination efficiency as high as 14.11%;Layer ventilation efficiency of particulate matter in the form of rule out less affected by temperature,working condition of the most efficient for the room temperature is 27? high wind speeds,ruled out 9.8%of the particulate matter.The work of this paper provides some experience and data for the control of microbial pollution and the prevention and control of infectious diseases.