Drag constants for common indoor bioaerosols

Abstract

In practice, the drag coefficient of a particle is usually calculated using empirical relationships obtained by generalizing experimental data. This study demonstrates that using the default Stokes’ law settings in FLUENT to computationally predict the drag coefficients for bioaerosol deposition is not really appropriate: the average fractional bias is 7% and the average normalized mean square error is 15%. Comparatively, the errors for bacteria (−12% to 24%) are larger than those for fungi (−8% to 26%). These errors, however, can be minimized by selecting a suitable drag constant, which can be determined based on the bioaerosol diameter. The average drag constants for bacteria were shown by the results to vary from 0.25 to 3.1, which are much smaller than the default value of 24, whereas the values for fungi were generally larger and in a wider range. This study also investigated the correlation between the drag coefficient and Reynolds number for common indoor bioaerosols with diameters between 0.69 and 8.6 µm. The outcome of this study would therefore provide a good reference point for future estimation of the deposition distribution patterns of various common indoor bioaerosols.