Preface

Hydraulic transients also referred to as fluid transients or water hammer usually cause leakage and rupture of pipelines. Since pressure rises are responsible of these accidents, engineers, and researchers are always trying to predict the pressure history in given hydraulic plants. This purpose requires in fact accurate modelling and calculation. Perhaps, readers who are interested in fluid mechanics have met at least one complicated situation revealing water hammer. Indeed, this phenomenon is not simply solved; partial differential equations are present, where the continuity equation and the equation of motion are used. Moreover, water hammer results in transient cavitation (vaporous cavitation and gaseous cavitation), which is a combination of thermodynamic and hydraulic phenomena. Transient cavitation is destructive for hydraulic plants. The entire content of this book is a mathematical and numerical study of transient cavitation in pipelines. The emphasis is made on coupled modelling and its numerical calculation. During several years of research, the author has focused on the accuracy of the numerical result. Different models, methods and assumptions are tested in order to be close to the experimental result. These are detailed in the present book. The simulation of vaporous cavitation and gaseous cavitation by use of coupled modelling is attempted to be useful. The improvement of the numerical simulation leads to the improvement of the design of pipes in hydraulic engineering. Two types of pipelines will be considered: the quasi-rigid elastic pipelines (metal and concrete) and the VE pipelines (polyethylene). Experimental results from the literature is used to validate the proposed models. The first chapter which is a review of the literature describes the main previous works on fluid transient in pipelines. The mathematical formulations of water hammer and cavitation are detailed in the second chapter. The mathematical modelling detailed concerns water hammer and cavitation. The numerical resolution of the various models using the MOC is presented in the third and the fourth chapters. Chapter 3 describes the numerical resolution proposed for the water hammer models, while the numerical modelling of transient cavitation is the subject of the fourth chapter. The results of the numerical simulation of water hammer and cavitation in elastic pipelines are introduced and discussed in the fifth chapter where the WSA scheme is highlighted. The final chapter is reserved for the simulation of water hammer and cavitation in VE pipeline.