This article deals with the study of the development and application of the high-order upwind ADBQUICKEST scheme, an adaptative bounded version of the QUICKEST for unsteady problems (Commun. Numer. Meth. Engng 2007; 23:419-445), employing both linear and nonlinear convection term discretization. This scheme is applicable to a wide range of computational fluid dynamics problems, where transport phenomena are of special importance. In particular, the performance of the scheme is assessed through an extensive numerical simulation study of advection-diffusion problems. The scheme, implemented in the context of finite difference methodology, combines a good approximation of shocks (or discontinuities) with a good approximation of the smooth parts of the solutions. In order to assess the performance of the scheme, seven problems are solved, namely (a) advection of scalars; (b) non-linear viscous Burgers equation; (c) Euler equations of gas dynamics; (d) Newtonian flow in a channel; (e) axisymmetric Newtonian jet flow; (f) axisymmetric non-Newtonian (generalized Newtonian) flow in a pipe; and (g) collapse of a fluid column. The numerical experiments clearly show that the scheme provides more consistent solutions than those found in the literature. From the study, the flexibility and robustness of the ADBQUICKEST scheme is confirmed by demonstrating its capability to solve a variety of linear and nonlinear problems with and without discontinuous solutions

SUMMARYThis paper is concerned with the numerical solutions of time dependent two-dimensional incompressible flows. By using the primitive variables of velocity and pressure, the Navier-Stokes and mass conservation equations are solved by a semi-implicit finite difference projection method. A new bounded higher order upwind convection scheme is employed to deal with the non-linear (advective) terms. The procedure is an adaptation of the GENSMAC (J. Comput. Phys. 1994; 110:171-186) methodology for calculating confined and free surface fluid flows at both low and high Reynolds numbers. The calculations were performed by using the 2D version of the Freeflow simulation system (J. Comp. Visual. Science 2000; 2:199-210). In order to demonstrate the capabilities of the numerical method, various test cases are presented. These are the fully developed flow in a channel, the flow over a backward facing step, the die-swell problem, the broken dam flow, and an impinging jet onto a flat plate. The numerical results compare favourably with the experimental data and the analytical solutions.

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A transformada wavelet contínua constitui poderosa ferramenta para análise multiescala de dados. Ela tem amplas aplicações na Física, na Matemática, nas Ciências Naturais e, inclusive, grande apelo nas engenharias, computação eáreas de tecnologia e inovação. Do ponto de vista introdutório, a transformada wavelet tem sido abordada amplamente em trabalhos anteriores. Assim, esta apresentação dáênfase ao uso dessa técnica em situações teóricas e práticas que normalmente não são exploradas; porém fundamentais para um uso mais adequado, ou mesmo correto, dessa ferramenta. Um embasamento consistente possibilita, sobretudo, uma extensão de sua aplicação para novas pesquisas, facilitadas pela disponibilidade de programas e ferramentas gratuitas e, até, várias dessas sob a forma de recursos de livre distribuição (free softwares). Por critério de escolha dos autores, apresentam-se, neste artigo, conceitos e exemplos de técnicas que podem ser de grande interesse para vários tipos de estudos na Física e em outrasáreas correlatas. Este texto destina-se a pesquisadores, professores e estudantes de pós-graduação, com a possibilidade de atender ainda necessidades de estudantes dosúltimos anos de graduação. Palavras-chave: wavelet, sinais multiescala, análise de sinais.The continuous wavelet transform is a powerful tool for multiscale data analysis. It has wide applications in physics, mathematics, natural sciences and even great appeal in engineering, computing and areas of technology and innovation. As an introductory point of view, the wavelet transform has been widely addressed in previous works. Thus, this presentation emphasizes the use of this technique in theoretical and practical situations that are not usually explored, but situations that are fundamental to a better use, or even a correct use, of this tool. Consistent bases enable mainly extensions of wavelet application to new investigations, that are facilitated by the availability of free programs and tools, and even several of these in completely available distribution of resources (free softwares). The content of this article, by the authors' choice criteria, presents concepts and examples of techniques that can be of great interest for various studies in physics and other related areas. This text is aimed at researchers, teachers and graduate students, with the possibility of still meet the preparation needs of students at last undergraduation stage. Keywords: wavelet, multiscale signals, signal analysis. IntroduçãoA teoria wavelet causou um frenesi na comunidade científica nasúltimas décadas e gerou um fenômeno de interesse, na pesquisa e na aplicação, com crescimento exponencial, gerando dezenas de milhares * Endereço de correspondência: margarete.domingues@inpe.br.de publicações, patentes e prêmios internacionais associados [8]. O leitor e sua família já participam e conhecem os efeitos desse fenômeno, tanto ao utilizar as imagens jpeg de um celular que podem ser enviadas por internet, quanto ao assistir os filmes de animação 3D, ou mesmo a ter seus dados bio...