No abstract

This paper investigates thermal walls behavior as elements of buildings and low-consumption energy residences. The problem is formulate based on the transient and unidimensional model, and numerically solved using the finite volumes method to discretize space and the implicit formulation to discretize time. Numerical tests were realized to optimize the mesh. Three different materials, heat transfer coefficient and color incorporation were tested in each wall layer A and B. The influence of these variations in the internal wall was calculated for each case. It was found that the best material for A and B walls are plaster mortar and common brick, respectively. This is a result of the inverse correlation between thermal resistance and the heat transfer rate. For a lower temperature in the external and internal walls, the thickness ratio for the external wall was  < 0.5 and for the inner wall was  > 0.5. The best value of absorptivity was 0.156 and the external heat transfer coefficient was variated to increase heat change. With all these parameters analyzed, it was possible to decrease significantly the heat transfer to the inner space and enhance the thermal comfort.

In this work, a numerical study of flow around an airfoil with wavy leading edge is presented at a Reynolds number of 3X106. The flow is resolved by considering the RANS (Reynolds Average Navier-Stokes)equations. The baseline geometry is based on the NACA 0021 profile. The wavy leading edge has an amplitude of 3% and wavelength of 11%, both with respect to the airfoil chord. Cases without and with wavy leadingedges are simulated and compared. Initially, studies of the numerical sensitivity with respect to the obtained results, considering aspects such as turbulence modeling and mesh refinement, are carried out as well as bycomparison with corresponding results in the literature. Numerical data such as pressure distribution, shear stress lines on the wing surface, and aerodynamics coefficients are used to describe and investigate the flowfeatures around the wavy leading airfoil. Comparisons between the straight leading edge and the wavy leading edge cases shows an increase of the maximum lift coefficient as well as stall angle for the wavy leading edge configuration. In addition, at an angle of attack near the stall, the present numerical results shows an increase of the drag coefficient with the wavy leading edge airfoil when compared with the corresponding straight leading edge case.

No abstract

<p class="04CorpodoTexto">Este trabalho apresenta o estudo numérico do escoamento e das características aerodinâmicas em aerofólios simétrico e assimétrico sem e com flap. Um modelo bidimensional, permanente e viscoso é adotado no problema. As equações da conservação de massa (Continuidade) e da conservação de movimento (Navier-Stokes) são diferenciadas pelo método dos volumes finitos através do software CFD (<em>Computational Fluid Dynamics</em>) ANSYS/Fluent™. Inicialmente o código numérico é validado com a comparação dos resultados obtidos numa simulação para um aerofólio da série NACA 4 dígitos sem flap com os resultados apresentados na literatura. Em seguida buscou-se averiguar como se comporta os campos de pressão e velocidade, as linhas de corrente, os coeficientes de sustentação e arrasto para os aerofólios simétrico (NACA 0012) e assimétrico (EPLLER 423) sem e com flap. Por fim é verificado qual aerofólio é mais eficiente aerodinamicamente.</p>