The spread of the novel coronavirus disease (COVID-19) continues to show that geographic barriers alone cannot contain the virus. Asymptomatic carriers play a critical role in the nature of this virus, which is rapidly escalating into a global pandemic. Asymptomatic carriers can inadvertently transmit the virus through the air stream. Many diseases can infect human bodies with tiny droplets or particles that carry various viruses and bacteria that are generated by the respiratory system of infected patients. This article presents the numerical results of the spread of droplets or particles in a room. The proposed numerical model in this work takes into account the sedimentation of particles or droplets under the action of gravitational sedimentation and transport in the room during the process of breathing and sneezing or coughing. Three different cases are numerically investigated taking into account normal breathing and coughing or sneezing, respectively, and three different rates of particle ejection from the mouth are considered. Navier–Stokes equations for incompressible flows were used to describe three-dimensional air flow inside ventilated rooms. The influence of ventilation rate on social distancing is also computationally investigated. It was found that particles can move up to 5 m with a decrease in concentration in the direction of the air flow. The conclusions made in this work show that, given the environmental conditions, the two meter social distance recommended by WHO is insufficient.

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In this work, a computational simulation of the pollutants spread generated during fuel combustion at Ekibastuz SDPP-1 and their chemical reaction in the atmosphere have been presented. Using the example of a real thermal power plant (Ekibastuz SDPP-1), the dispersion NO, NO 2 , CO and products NO 2 , HNO 3 , CO 2 during a chemical reaction with oxygen was modeled. The numerical method was verified by solving three test problems and the received computational solutions were compared with data from the measurement and the computational data of other authors. The purpose of the work was to investigate the pollution level at various ranges from the source. As a result, the mass fraction of the concentration and product during a chemical reaction were determined. According to the obtained data, with increasing distance from the source, the concentration of pollution spreads more widely under the influence of diffusion. The farther the distance from the chimney, the lower the concentration of the substance and products. Thus, the obtained computational values may allow in the future predicting the optimal distance from residential areas for the construction of thermal power plants, at which the concentration of emissions will remain at a safe level.

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