Modelling the transport of expelled cough particles using an Eulerian approach and the variational multiscale method

Abstract

Modelling the dispersion and deposition of expelled particles in an indoor environment is presented in this paper. The airflow is described by the incompressible Navier–Stokes equations, and the dispersion of a group of particles is modelled through an Eulerian transport equation coupled to the system of Navier–Stokes equations. The turbulent airflow and turbulent dispersion of particles are modelled by the variational multiscale method. Boundary integral terms are presented for weakly imposing essential boundary conditions as a wall model, and for modelling the deposition of particles on no-slip walls. The formulation is validated against experimental measurements and numerical data of the concentration of particles in a model chamber with success. A study case is presented where a coughing event is modelled in a real-life indoor environment under two different ventilation scenarios, where the first scenario considers only the air supply provided by the ceiling vents, while the second scenario considers in addition the air supply provided by two wall-mounted air conditioners. The coughing event is represented through realistic boundary conditions taken from experimental measurements. The dispersion and deposition patterns are compared between the two ventilation scenarios. The results show robustness of the presented formulation and encourages further developments in future works.