On second-order closure modeling of turbulent diffusion in a convective boundary layer

A second-order closure turbulence model is used to simulate the plume behavior of a passive contaminant dispersed in a convective boundary layer. A time-splitting finite element scheme is used to solve the set of partial differential equations. The second-order closure model can describe the plume 'lift off' and 'descending' behavior and agrees with recent findings from laboratories and Large Eddy Simulations (LES). The authors also compare the second-order closure model with the commonly used eddy diffusivity or K-diffusion model for the same meteorological conditions. The time-splitting finite element scheme requires about 2.5 to 7.6 times the CPU time used by the K-diffusion model.