In the light of rapidly increasing applications of large-eddy simulations (LES), it is deemed necessary to impose some quality assessment measures for such studies. The verification of LES calculations is difficult because of the fact that both the subgrid scale (SGS) model contribution and numerical discretization errors are functions of the grid resolution. In this study, various indexes of quality measures, hereafter referred to as LES̱IQ, are proposed. The recommended LES̱IQ is based on the Richardson extrapolation concept. This method has been applied to various cases and the calculated LES̱IQ results are compared with the relative total experimental and direct numerical simulation (DNS) error, defined as IQ̱EX and IQ̱DNS, respectively. It is postulated that in practical applications of LES, numerical dissipation will always be a significant part of the overall dissipation, and it must be accounted for in any assessment of the quality of LES. It is further suggested that LES̱IQ of 75% to 85% can be considered adequate for most engineering applications that typically occur at high Reynolds numbers; the proposed index is an indicator of good resolution (i.e., verification), but not necessarily a good or accurate model (i.e., validation).

The question of whether influenza is transmitted to a significant degree by aerosols remains controversial, in part, because little is known about the quantity and size of potentially infectious airborne particles produced by people with influenza.

Size-fractionated aerosol particles were collected in a hospital emergency department to test for airborne influenza virus. Using real-time polymerase chain reaction, we confirmed the presence of airborne influenza virus and found that 53% of detectable influenza virus particles were within the respirable aerosol fraction. Our results provide evidence that influenza virus may spread through the airborne route.

A random flow generation (RFG) technique is presented, which can be used for initial/inlet boundary generation in LES (Large-Eddy-Simulations) or particle tracking in LES/RANS (Reynolds-Averaged Navier-Stokes) computations of turbulent flows. The technique is based on previous methods of synthesizing divergence-free vector fields from a sample of Fourier harmonics and allows to generate non-homogeneous anisotropic flow field representing turbulent velocity fluctuations. It was validated on the cases of boundary layer and flat plate flows. Applications of the technique to LES and particle tracking are considered.

Airborne particles containing influenza and RSV RNA were detected throughout a health care facility. The particles were small enough to remain airborne for an extended time and to be inhaled deeply into the respiratory tract. These results support the possibility that influenza and RSV can be transmitted by the airborne route and suggest that further investigation of the potential of these particles to transmit infection is warranted.