Water Hammer Simulations

Stefano Mambretti currently serves as a visiting professor at the Universidade Estadual de Campinas, in Brazil. Previously, he was Associate Professor of Hydraulics at the Faculty of Engineering of the Politecnico di Milano. He graduated in Civil Engineering at the Politecnico in 1991 (winning the "Noseda prize" as best graduate in Hydraulics that year) and was awarded a PhD in Hydraulic Engineering in 1995. In 1997 he was appointed as Vice Chief of Public Works in an important municipality, in 1999 he became Assistant Professor in Hydraulics, and in 2003 he was appointed Associate Professor. Stefano also worked as a private consultant, for a number of projects in urban infrastructures in Djibouti, Kuwait, Algeria, Tanzania, Iraq, gaining renowned expertise, mainly in the field of waterhammer. Dr. Mambretti is the author or co-author of numerous publications (peer-reviewed scientific papers, key-note lectures, conference papers, books, and technical reports) in the areas of water phenomena, as urban infrastructures (sewer and water distribution systems), fluid dynamics and rheology of debris and hyper-concentrated flows, water resources use and management, using both advanced laboratory and field observation techniques and mathematical simulation models. He is the co-editor of the WIT Press book Dam-Break Problems, Solutions and Case Studies published in 2009.

• Contents An old topic still not completely solved An old topic; Applications and problems; This book; The computer programs Compressible flow theory: basic concepts Instantaneous operations; Wave celerity; Velocity of operations; Non-negligible headlosses; Governing equations; Continuity equation; Momentum equation; The governing equations Simplified solutions The Allievi's method (1913); The non-elastic hypothesis; Governing equations; Comparisons; Graphical method Numerical solution of the governing equations: The method of characteristics Numerical solution; Initial and boundary conditions; Reservoir; Valve; Junction; The computer code; First simple application Numerical solution of the governing equations: finite difference methods The Courant - Friedrichs - Levy stability condition; The Lax - Wendroff method; Solving the governing equations; Boundary conditions; Asymmetrical schemes; Ghost cells; The computer code; Again the simple application Devices - Boundary conditions Surge tanks; Simple surge tanks; Different types of surge tanks; Air chambers; Relief valves and rupture disks; Centrifugal pumps; Other methods for controlling the pressures; The computer codes; The simple surge tank; The simple air chamber; Air chamber with headlosses; Air chamber and valve; Valve modelling: an example; Pumps Instabilities Vibrations; General remarks; Computer program for oscillating velocity; Transfer matrix method; General remarks; Application to hydraulic transients; Description of simple system: pipes; Description of simple system: valves and effluxes; Global matrix of a system; A simple application; Numerical instabilities; Changing CFL number; First order methods; Flux-limiters; Artificial dissipation Effects of air and cavitation Cavities; Formation of the cavities; Collapse of the cavities; Description of the motion in the presence of cavities; Changing of celerity; Water column separation; Additional resistance terms; Models; Parameters; Laboratory experiments; Experimental set-up; Experimental tests; Computer code Advanced models 2D models; Continuity equation; Momentum equation; Headlossess; Pezzinga's model; k - epsilon model; avitation; Release gaseous cavitation model; Second viscosity cavitation model;Numerical schemes; Further problems Case studies Simple pressure pipe for petroleum products in Djibouti; lant characteristics; Expected scenarios; Case 1; Case 2; Case 3; Conclusions; A more complex example for seawater treatment plant in Tanzania; Plant characteristics; Unsteady flow simulations: existing plant; Plant to be designed; No air chambers; Air chamber 3 m3 volume; Air chamber 5 m3 volume; Conclusions; A very complex example for seawater treatment plant in Algeria; The plant to be modelled; A peculiar device: energy recovery PX; Laboratory plant; Laboratory tests; Model of the seawater plant in Algeria; Conclusions;Final remarks References