URANS and DNS of a Cough-Induced Aerosol-Laden Jet Flow Interacting with a Large-Scale Circulation

This study investigates the dispersion of a cough-induced particle cloud in the presence of a large-scale circulation (LSC) predicted in an unsteady Reynolds-averaged Navier–Stokes simulation (URANS), and compares the results with those of a direct numerical simulation (DNS). Both simulations share identical initial conditions and domain sizes, but they differ in spatial and temporal resolution and their approach to turbulence. After the jet phase, it is found that the particles in the URANS have not advanced as far in the horizontal direction as those in the DNS. The shape of the URANS particle cloud is symmetric in the horizontal inlet midplane, whereas in the DNS the particles appear to be irregularly distributed. In the well-developed puff phase, the particles of URANS have moved less far in horizontal direction than those of DNS. Although the lateral dispersion of the URANS particles is similar to that of the DNS particles, the top view shows a cone-shaped pattern for the URANS particles, whereas those of the DNS have a uniform distribution. The major difference between the URANS and DNS results in the late puff phase is the thicker and stronger boundary layer near the upper wall of the URANS, which impedes the vertical ascent of the particles, resulting in a stronger overall circulation intensity throughout the domain. In the jet phase, both URANS and DNS predictions exhibit good agreement in the vertical particle probability density distribution (PDF). However, this agreement is not observed in the well-developed and late puff phases.