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ENCIT 2020
18th Brazilian Congress of Thermal Sciences and Engineering
DEVELOPMENT AND PARAMETRIC ANALYSIS OF A NUMERICAL WIND FLOW MODEL FOR COMPLEX TERRAIN IN OPENFOAM
Submission Author:
Gabriel Dumont , RS
Co-Authors:
Gabriel Dumont, Adriane Prisco Petry, William C. Radünz
Presenter: Gabriel Dumont
doi://10.26678/ABCM.ENCIT2020.CIT20-0732
Abstract
This work is based on the CFD modelling of atmospheric boundary layer flows over complex terrains. The employed CFD toolbox is OpenFOAM, which stands out as a robust open source alternative to conventional programs, and the studied cases involve computational domains based on two real life hills – Askervein Hill in Scotland and Bolund Hill in Denmark, the latter being a highly complex terrain. The model is validated through a simulation in a two-dimensional plain terrain with uniform rugosity, where the atmospheric surface layer profile should remain unchanged; this is achieved by modifying the standard wall functions and altering the constants of the standard k-ε turbulence model. After validation, the model is applied to computational domains which include the hills, and a sensitivity analysis is undertaken by varying mesh refinement, the employed divergence scheme, and the turbulence model’s parameters. The results showed that all models underpredicted the turbulent kinetic energy at the lee of both hills, though the effect is much more pronounced in simulations that used the upwind scheme, probably due to numerical diffusion; however, although the higher-order schemes better predict the steep turbulent kinetic energy gradients, they may also overpredict the velocity gradients in the regions close to the ground. As for the turbulence models, it was shown that determining the constants by fitting meteorological data did not necessarily lead to a better result. In general, especially for regions above 2 meters, simulations that employed modified constants for the k-ε model and higher-order divergence schemes presented wind profiles that were in better agreement with the measured data, with a relative error under 25% for both hills.
Keywords
atmospheric boundary layer, Complex terrain, Parametric analysis, OpenFOAM
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