Improving a Two-Equation Turbulence Model for Canopy Flows Using Large-Eddy Simulation
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Large-eddy simulations of the neutrally-stratified flow over an extended homogeneous forest were used to calibrate a canopy model for the Reynolds-averaged Navier–Stokes (RaNS) method with the \(k-\varepsilon \) turbulence model. It was found that, when modelling the forest as a porous medium, the canopy drag dissipates the turbulent kinetic energy (acts as a sink term). The proposed model was then tested in more complex flows: a finite length forest and a forested hill. In the finite length forest, the destruction of the turbulent kinetic energy by the canopy was overestimated near the edge, for a length approximately twice the tree height. In the forested hill, the model was less accurate inside the recirculation zone and overestimated the turbulent kinetic energy, due to an incorrect prediction of the production term. Nevertheless, the canopy model presented here provided consistent results in both a priori and a posteriori tests and improved the accuracy of RaNS simulations with the \(k-\varepsilon \) model.
KeywordsForest canopy \(k-\varepsilon \) turbulence model Large-eddy simulation Model calibration
A. Silva Lopes and J. Viana Lopes are research fellows under Programa Ciência of the Portuguese Foundation for Science and Technology (FCT). These research activities were developed as part of the work program of the Center for Wind Energy and Atmospheric Studies, a unit of the Portuguese research network, sponsored by the Portuguese Foundation for Science and Technology (FCT).
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