In the present work, the flow through tube banks is studied in order to understand the random and transient behavior of the instabilities and phenomena that occur in the first rows of tube banks and propagates to its interior. The study is performed using hot wire anemometry in an aerodynamic channel and flow visualizations in a water channel. Three tube banks with square arrangement and pitch-to-diameter ratios of 1.26, 1.4 and 1.6 were studied. The Reynolds number range for the velocities measurements, computed with the tube diameter and the flow velocity in the narrow gap between tubes, was 7-8x10 4. Continuous and discrete wavelets analyses were applied to decompose the velocity results, thus allowing the analysis of phenomena in a time-frequency domain. Visualizations in a water channel were made, using a dye injection directly in the flow, in order to help the understanding about the phenomena found. A tube bank with a square arrangement and 1.26 pitch-to-diameter ratio was used, and the experiments were performed in a Reynolds number range of 3-4x10 4. The main results show the presence of instabilities generated from the second row of the tube bank, which propagates to the interior of the bank, generating a behavior where the three orthogonal components of the flow are equally important. The three-dimensional behavior of the flow is responsible for a redistribution of mass inside of the bank of tubes that leads to velocity values and Strouhal numbers not expected for the studied geometry.

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This article discusses the advantages of measuring wave orbital velocities in coastal two-dimensional physical models in addition to free surface profiles. A brief presentation of linear theory for partial standing wave is made and early experimental works on this subject are reviewed. Since 2005, additional experiments have been conducted on wave flumes in Brazil (INPH, IPH/UFRGS) and in Portugal (LNEC), in order to characterize wave patterns in terms of velocity data obtained by ADVs. A few questions are posed in the conclusion of the article, which aim at suggesting special care on the interpretation of velocity data, as used today, as well as proposing further research on the subject.