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Inlet boundary conditions at the supply opening play an important role in the accuracy and reliability of computational fluid dynamics (CFD) simulations for indoor airflow. A non-exhaustive overview of past CFD simulations of ventilation flow in generic enclosures indicates that uniform hypotheses of inlet boundary conditions are commonly used. However, due to thermal effects and a complex air supply system geometry, constant values of inlet airflow quantities can be insufficient for an accurate simulation of non-isothermal ventilation flow. In addition, this can lead to biased conclusions on the performance of turbulence models and other computational settings. To assess this issue, a well-documented experiment on non-isothermal mechanical ventilation with detailed information of inlet conditions from the literature is used in this study. Different turbulence models and inlet boundary conditions are validated, including seven steady Reynolds-averaged Navier-Stokes (RANS) models, six methods of imposing inlet air velocity, three methods of specifying air temperature, and a wide range of turbulence quantities. The parametric study demonstrates that in this particular case, i.e., cold air supply from a single round nozzle diffuser close to the ceiling, ω-based turbulence models perform better than the ε-based turbulence models. The impacts of different methods to specify inlet air temperature profile and turbulence quantities on the simulation results are not significant. However, if the inlet airflow direction is not taken into account appropriately, significant deviations are observed between CFD simulations and experimental data. • Detailed analyses of influence of inlet boundary conditions in CFD simulations. • Validation of RANS CFD simulations with measurement data from the literature. • ω-based turbulence models perform better than the ε-based turbulence models. • The inlet flow conditions can have a very strong effect on overall flow pattern. • Care should be taken in validation studies when inlet conditions are not known. [ABSTRACT FROM AUTHOR]

• We evaluate effects of ventilation and social distancing on aerosol exposure. • We study transport dynamics of exhaled aerosols in human breathing zone. • Ventilation strategy notably affects the airborne infection risk. • Buoyancy-driven airflow can cause elevated human exposure to viral aerosols. • A 2 m social distance may not effectively reduce the risk of infectious aerosols. Airborne transmission of virus via respiratory aerosols plays an important role in the spread of infectious diseases in indoor environments. Ventilation and social distancing are two major control strategies to reduce the indoor airborne infection risk. However, there is a present lack of science-based information on how the human exposure to viral aerosols vary with ventilation condition and social distance. The objective of this study is to explore the transport patterns of respiratory aerosols in occupied spaces and assess the occupant exposure risk under different ventilation strategies, social distances and aerosol emission modes. The study results show that buoyancy-driven flow regime (can be found in many residential settings) can lead to a longer transmission distance and elevated exposure to viral aerosols than the mixing airflow, thereby causing higher cross-infection risk in indoor environments. The results also suggest that a 2 m (6 ft) social distance alone may not ensure control of indoor airborne infections. [ABSTRACT FROM AUTHOR]