Predictive model for scalar concentration fluctuations in and above a model plant canopy

A Lagrangian stochastic (LS) implementation of an interaction by exchange with the conditional mean (IECM) micromixing model is used to estimate concentration fluctuations in plumes dispersing from an in-canopy, localized source into a model plant canopy flow. The sensitivity of the LS-IECM model to the underlying Eulerian flow statistics is investigated by comparing model predictions from simulations driven by two interpolations of the same water-channel flow data. The two simulations showed minor differences in the predicted mean concentration but marked differences in the standard deviation, skewness and kurtosis of concentration. This is shown to be caused by differences in the turbulent kinetic energy (TKE) dissipation rates between the two interpolations and their effects on the IECM model. The LS-IECM model predictions of the first four moments of the scalar concentration field showed fair to good conformance (depending on which TKE dissipation rate is used) with experimental water-channel dispersion data.