الفهرس 
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Abstract
In the present thesis, the continuity and momentum equations were solved using the Method of characteristics to simulate the water hammer phenomenon taking into account the effect of pipe wall viscoelasticity and unsteady friction of fluid flow. In order to study the effect of extended blockage existence in the pipeline, a MATLAB code was developed to deal with both cases: simple single pipeline and complex series pipes. Because of the vital role that boundary conditions play in the profile of the generated pressure wave, they were mentioned in this thesis. Code developed was validated with previous experimental data for the case of single pipe and for complex pipeline. In addition to that, a simple Reservoir-Pipe-Valve test rig was constructed using Polyvinyl chloride (PVC) pipe. The experimental data extracted from the test rig were compared with the numerical results of the code for both simple and complex pipelines. The code could predict the pressure head fluctuations quite accurately in the case of simple pipe. However, in case of complex series pipeline, it could predict the maximum pressure head for the first two peaks, and because of frequency change between the two results, a discrepancy is noticed clearly which increases with time. This discrepancy may be ascribed to the lack of the one-dimensional model to predict gradually the flow at the abrupt. In addition, neglecting the total effect of Fluid-Structure interaction may lead to this discrepancy too. Then a sensitivity analysis was carried out to investigate the effect of some essential parameters on the pressure wave profile generated in viscoelastic pipes. This study reveals that the attenuation of the pressure wave depends on the viscoelasticity of the pipe wall material. The more slope of the creep curve, the more viscoelastic properties of the material. In addition, the maximum pressure head rise does not depend on the reflection time of the wave only, but depends also on the closing protocol of the valve and its hydraulic characteristics.