The present work is motivated by phenomena occurring in the flow field around structures partly submerged in water. A three-dimensional (3D) unsteady flow around a rectangular cylinder is studied for four different submergence ratios by using computational fluid dynamics (CFD) tools with the large eddy simulation (LES) turbulence model. The simulation results are compared to particle image velocimetry (PIV) measurements at the Reynolds number Re = 12,100 and the Froude number Fr = 0.26. The focus in our investigation is on the characterization of the behavior of vortex structures generated by separated flow. Another target in the study is to obtain a better knowledge of the hydrodynamic forces acting on a semi-submerged structure. The computed force coefficients are compared with experimental measurements.

In recent years, water utilities have made worldwide investments targeted to the implementation of an effective monitoring system and the installation of pressure-reducing valves in strategic nodes of water distribution networks. In fact, these interventions are considered fast and effective solutions to address at least two main concerns of modern water utilities: leakage reduction and energy efficiency. The present paper, on the basis of a database of working conditions of installed pressure-reducing valves, discusses the range of applicability of the GreenValve system (GVS) as an alternative solution to improving standard pressure-reducing valve capabilities. The device is able to recover energy, and it can be used to create a stand-alone monitoring node with remote control ability, optimizing the network from an energetic, functional, and hydraulic point of view.

Energy harvesting from dissipation processes during flow control is a challenge for many different applications. Common usage of many plants and systems requires control valves to dissipate overpressures. GreenValve is an innovative control device designed to control the flow and harvest the energy that is normally wasted during the throttling process. A vertical axes water turbine resides within the valve body to improve regulation efficiency and recover part of the energy that would be dissipated. In the present work, GreenValve and the results of an experimental campaign to characterize its functioning are discussed. Then some real scenarios have been considered as potential applications. Regulation as a function of time has been considered to calculate the instantaneous energy dissipated through the throttling process and evaluate case by case the amount of harvestable energy. At the end some considerations on the effectiveness of the GreenValve are presented.

Microscopy techniques can readily visualize the finest details of embryo vasculature, but still lack to provide a complete three‐dimensional representation of blood flow parameters. We present an in‐vivo 3D imaging technique, able to reconstruct the blood cell velocity vector over a large volume of zebrafish embryos. This low cost and relatively simple technique is exploited to quantitatively assess blood velocity in the zebrafish tail at different stages of development. (© 2013 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)