Violent respiratory diseases, i.e., coronavirus (COVID-19), spread through saliva in coughs and sneezes or are even exhaled in the form of microbial pathogen micro-droplets. Therefore, in this work, a comprehensive fully coupled Eulerian–Lagrangian method has been applied for infection control, thus leading to a deeper understanding of the saliva-disease-carrier droplet transmission mechanisms and also of their trajectory tracking by using the OpenFOAM package. This model determines the droplet–air interactions, the breakup process, and turbulent dispersion forces on each micro-droplet that is expelled within the respiratory tract in a correct way. By examining a broad range of initial velocities, size distributions, injection angles of saliva micro-droplets, and mouth opening areas, we predict the maximum opening area that can be driven by micro-droplets. One important contribution of this work is to present a correlation for the length and width of the overall direct maximum reach of the micro-droplets, driven by a wide range of mild coughs to intense sneezes. Our results indicate that the movement of the expelled droplets is mainly influenced by their size, angle, velocity, and environmental factors. During a virus crisis, like COVID-19, this paper can be used to determine the “social distance” between individuals to avoid contamination, by inhaling or touching their bodies, due to these saliva-disease-carrier droplets in sneezing, at various social distance positions such as face-to-face, meeting standing, and near equipment. The safe distance must be increased to around 4 m during a sneeze. By wearing a face mask and by bending the head during a sneeze as a protective action, we can reduce the contamination area to one-third and three-quarters, respectively. Furthermore, the dispersion of the film of the expelled saliva micro-droplets and the spatial relationship between the subjects, which affects the airflow inside the room, are also analyzed in detail.

The paint shop plant, as the largest energy consumer in the automotive manufacturing process, requires special attention to optimize energy efficiency and thermal management, reduce environmental impact and diminish the total costs to improve marketability. The current review covers the description of the automotive paint shop, recognition of the paint film layers, characterization of the paint spray applicators, evolution of their technology's advancement, explanation of the coating processes development, and investigation of the curing ovens thermal procedure in an automotive production stage. After systematically recalling pioneering studies dealing with the coating techniques and opening strategies, this paper focuses on reviewing recent findings conducted with improved modern methods in this subject area for higher sustainability and efficiency. Critical performance factors in developing surface durability, corrosion protectivity, paint material consumption, and environmental pollution are discussed. Focus is brought to the electrostatic spray-painting procedure flow physics understanding, particularly the complicated three-dimensional behaviors of paint droplets formation, distribution, control, and deposition on the body in constructed spray plums. Then, the baking and drying process of the produced film layer in the curing oven is precisely reviewed. The review additionally aids in the identification of knowledge gaps in the literature that should be addressed in future research.