NUMERICAL COMPARISON OF PIPE-COLUMN SEPARATION MODELS

Results comparing six column-separation numerical models for simulatin g localized vapor cavities and distributed-vaporous cavitation in pipe lines are presented. The discrete vapor-cavity model (DVM) is shown to be quite sensitive to selected input parameters. For short pipeline s ystems, the maximum pressure rise following column separation can vary markedly for small changes in wave speed, friction factor, diameter, initial velocity, length of pipe, or pipe slope. Of the six numerical models, three perform consistently over a broad number of reaches. One of them, the discrete gas-cavity model, is recommended for general us e as it is least sensitive to input parameters or to the selected disc retization of the Three models provide inconsistent estimates of the m aximum pressure rise as the number of reaches is increased; however, t hese models do give consistent results provided the ratio of maximum c avity size to reach volume is kept below 10%.