A study on tubulence models for diffusion and absorption of contaminant and carbon dioxide within vegetation

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In this study, we proposed two kinds of turbulence models for diffusion and absarption oficontamioant and carbon dioxide within vegetation. One (k-ε) type model and the other is a LES(Large Eddy Simulation) model. In cam of (k-ε) model, we adopt the procedure where we took the ensemble avenges and then the spatial averages of the basic equations. A filter was adopted for the spatial average. We assumed that tie filter was sufficiently smooth, though it was top-hat type. The drag force due to pressure and strain was analytically derived from taking the ensemble-averaged Navier-Stokes equation. Moreover, the equations of turbulent energy and viscous dissipation rate were derived from the basic equations. The effects of vegetation on the equations of turbulent energy and viscous dissipation rate were modeled and the equations were closed The validation was tried by comparing the results from the model with the measured data. In case of LES model, we adopted the sufficiently smooth top-bat filter. Although Smagorinsky-type LES models are usually used, we adopted a one-equation LES model. Because the wake production term which appears in the subgrid-scale turbulence equation is not negligible. The one-equation LES model was validated by comparing the result of the model with the measured data.