Atmospheric Dispersion
There are a wide variety of atmospheric dispersion models available to predict time-averaged exposure concentrations, but an individual receptor in a dispersing plume will see large variations in the instantaneous concentration caused by the natural variability of turbulent mixing. Acute toxic effects, odour detection, and other receptor responses are typically very sensitive to these high frequency concentration fluctuations.
Coanda has extensive experience with physical modelling of dispersion in our water channel, coupled with high speed data acquisition to measure concentration fluctuations. We have also developed software to produce ensembles of simulated exposure concentration time series with statistics and correlations that match the real atmospheric dispersion process.
This image shows an instantaneous 2D LIF representation of a scalar, 704 mm downstream of the release point. The graph to the right shows the mean concentration of the scalar at multiple heights. This data was collected at 300hz for 2000 seconds using Coanda’s 1D LIF system.
Many dispersion models that exist today can only predict time-averaged concentrations and not the potentially fatal fluctuations that exist in the real world. This graph shows the dramatic effect of these fluctuations.