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Abstract(s)
O objetivo principal da seguinte tese ´e a análise e validação do comportamento do modelo de floresta do software de CFD (Computer Fluid Dynamics) Windie, nomeadamente em simulações usando as equações RaNS (Reynolds-averaged Navier–Stokes time-averaged equations) com o modelo de turbulência k − ε atmosférico. Neste trabalho ´e feita a reprodução e comparação com resultados experimentais e resultados em LES (Large eddy simulation) de escoamentos em regiões de colinas suaves com e sem floresta. O software Windie ´e uma ferramenta de CFD, desenvolvida com base no trabalho percursor de F.A. Castro. (1997). Esta ferramenta ´e especializada no estudo de implantação de parques eólicos através de simulações em topografias complexas, com ou sem floresta. Os resultados experimentais foram obtidos através de Poggi and Katul (2008), que investiga a variação de velocidade e espectro sob a influência da topografia e floresta densa e Patton and Katul (2009), que igualmente avalia a variação de velocidade sobre uma topografia, mas comparando diferentes densidades de floresta através de simulações em LES. As condições de escoamento do presente trabalho são de um escoamento turbulento, incompressível em regime estacionário e definido através do modelo de turbulência k−ε atmosférico, baseado no método das médias de Reynolds (RaNS - Reynolds Averaged NavierStokes). As condições de cálculo têm como base a descrição do trabalho de Poggi and Katul (2008) e Patton and Katul (2009), representando um escoamento sobre uma topografia similar, mas onde nem todas as condições de fronteira foram possíveis de representar. A caracterização da floresta ´e feita através de um modelo avançado desenvolvido em Lopes da Costa (2007) que permitiu definir a densidade foliar ao longo da altura da floresta. Os resultados obtidos das simulações no Windie, foram processados de maneira a poderem ser comparados com os resultados dos artigos citados, para o caso de superfície descoberta e com diferentes densidades de floresta.
The main purpose of the following thesis is the analysis and validation of the behaviour of the forest model of CFD’s (Computer Fluid Dynamics) software Windie, specifically in simulations using RaNS (Reynolds-averaged Navier-Stocks time averaged equations) equations with the turbulence model k − ε atmospheric. In the present work, results of gentle hills regions’ flow with or without forest are reproduced and compared with Large eddy simulation (LES). Windie software is a CFD tool, developed based in the work of F.A. Castro. (1997). This tool is specialized in studying the implementation of wind farms through simulations in complex topographies, with or without forest. The experimental results were obtained through Poggi and Katul (2008), which investigates the velocity variation and spectrum under the influence of topography and dense forest. Patton and Katul (2009), also evaluates the speed variation over a topography but compares it with different forest densities using LES simulations. The flow conditions of the present work are based on a turbulent flow and incompressible in steady state. They are defined by the turbulence model k − ε, based on the Reynolds averages (RaNS - Reynolds Averaged Navier-Stocks). The calculation conditions are based on Poggi and Katul (2008) and Patton and Katul (2009). Although they represent a flow over similar topography, some boundary conditions were not possible to represent. The forest characterization is done through an advanced model, developed by Lopes da Costa (2007), that defines the leaf density along the height of the forest. The Windie simulations were processed and then compared with the results of cited articles, for cases with bare surface and different forest densities.
The main purpose of the following thesis is the analysis and validation of the behaviour of the forest model of CFD’s (Computer Fluid Dynamics) software Windie, specifically in simulations using RaNS (Reynolds-averaged Navier-Stocks time averaged equations) equations with the turbulence model k − ε atmospheric. In the present work, results of gentle hills regions’ flow with or without forest are reproduced and compared with Large eddy simulation (LES). Windie software is a CFD tool, developed based in the work of F.A. Castro. (1997). This tool is specialized in studying the implementation of wind farms through simulations in complex topographies, with or without forest. The experimental results were obtained through Poggi and Katul (2008), which investigates the velocity variation and spectrum under the influence of topography and dense forest. Patton and Katul (2009), also evaluates the speed variation over a topography but compares it with different forest densities using LES simulations. The flow conditions of the present work are based on a turbulent flow and incompressible in steady state. They are defined by the turbulence model k − ε, based on the Reynolds averages (RaNS - Reynolds Averaged Navier-Stocks). The calculation conditions are based on Poggi and Katul (2008) and Patton and Katul (2009). Although they represent a flow over similar topography, some boundary conditions were not possible to represent. The forest characterization is done through an advanced model, developed by Lopes da Costa (2007), that defines the leaf density along the height of the forest. The Windie simulations were processed and then compared with the results of cited articles, for cases with bare surface and different forest densities.
Description
Keywords
Atmospheric Flows Computational Fluid Dynamics RaNS