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The presence of protuberances on surfaces, for example, riv ets, screws and gaskets, can influence the boundary layer by accelerating the transit io from laminar flow to turbulent flow. In some cases this may be undesirable, since the t urbulent flow involves frictional forces greater than the ones at the laminar regim . There are some aspects of the flow in the boundary layer perturbed by a single roughness element that are not well understood. The aim of this work is to study the influence of an isolated roughness on the boundary layer. This study is a step towards to the understan ding of what can happen in more complex cases. The nature of this study is computationa l, therefore a Direct Numerical Simulation code is used. The immersed boundary method is used to represent the roughness in the flow on the surface. The numerical code is ver ified via the Method of Manufactured Solutions. Comparisons between experimental d a , Linear Stability Theory and numerical results are also used for the validation of the code. Results obtained with different roughness heights and variations in the pressure gradient allowed the analysis of the influence of a three-dimensional roughness element in bo u dary layer flows.

Simulação numérica direta de escoamento transicional sobre uma superfície contendo rugosidade