Sect 2. 317 tinuity surfaces 1. This suggests that a wake pressure Pw be associated with each flow past a bluff body, and that a wake parameter (2. 4) which plays the same role as the cavitation parameter (2. 1), be defined for the flow. This idea has been made the basis of a modified wake theory (ef. Sect. 11) which proves to be in good qu- titative agreement with pressure and drag measurements. It should be emphasized, however, that un h like the cavitation number, the wake parameter is a quantity which is not known a priori, and must be empirically determined in each case. (3) Jet flows. The problem of jet efflux from an orifice is one of the oldest in hydrodynamics and the first to be treated by Fig. 3a. the HELMHOLTZ free streamline theory. Of particular importance for engineering applications is the discharge coefficient Cd' which is defined in terms of the discharge Q per unit time, the pressure P, and the cross-sectional area A of the orifice, by the formula, (2. 5) where e is the fluid density. Two methods of measuring Cd have been most fre quently adopted. In the first the liquid issues from an orifice in a large vessel under the influence of gravity _,-____________ . , (Fig. 3 a), while in the second it 1 L is forced out of a nozzle or pipe under high pressure (Fig. 3 b).

Water Management Challenges in Global Change contains the proceedings of the 9th Computing and Control for the Water Industry (CCWI2007) and the Sustainable Urban Water Management (SUWM2007) conferences. The rationale behind these conferences is to improve the management of urban water systems through the development of computerbased methods. Issues such as economic globalisation, climate changes and water shortages call for a new approach to water systems management, which addresses the relevant technical, social and economic aspects. This collection represents the views of academic and industrial experts from a number of countries, who provide technical solutions to current water management problems and present a vision for addressing the global questions. The themes underlying many of the contributions include energy and material savings, water savings and the integration of different aspects of water management. The papers are grouped into three themes covering water distribution systems, sustainable urban water management and modelling of wastewater treatment plants. The water distribution topics cover asset and information management, planning, monitoring and control, hydraulic modelling of steady state and transients, water quality and treatment, demand and leakage management, optimisation, design and decision support systems, as well as reliability and security of water distribution systems. The sustainable urban water management topics include urban drainage systems, water reuse, social aspects of water management and also selected facets of water resources and irrigation. Computer control of wastewater treatment plants has been seen as less advanced than that of clean water systems. To address this imbalance, this book presents a number of modelling techniques developed specifically for these plants. Water Management Challenges in Global Change will prove to be invaluable to water and environmental engineering researchers and academics; managers, engineers and planners; and postgraduate students.

This textbook provides a coherent and structured overview of fluid mechanics, a discipline concerned with many natural phenomena and at the very heart of the most diversified industrial applications and human activities. The balance between phenomenological analysis, physical conceptualization and mathematical formulation serve both as a unifying educational marker and as a methodological guide to the three parts of the work. The thermo-mechanical motion equations of a homogeneous single-phase fluid are established, from which flow models (perfect fluid, viscous) and motion classes (isovolume, barotropic, irrotational, etc.) are derived. Incompressible, potential flows and compressible flows, both in an isentropic evolution and shock, of an ideal inviscid fluid are addressed in the second part. The viscous fluid is the subject of the last one, with the creeping motion regime and the laminar, dynamic and thermal boundary layer. Historical perspectives are included whenever they enrich the understanding of modern concepts. Many examples, chosen for their pedagogical relevance, are dealt with in exercises. The book is intended as a teaching tool for undergraduate students, wishing to acquire a first command of fluid mechanics, as well as graduates in advanced courses and engineers in other fields, concerned with completing what is sometimes a scattered body of knowledge.