Flow modeling in pressurized systems revisited

Assuming 1D flow in pressurized systems, transient analyses can be performe d using a number of well-established models, in the short-term timescale, p ractical problems are solved using either elastic or rigid models, whereas in the long-term scale a quasi-static model is more convenient. These model s can be obtained by simplifying the general equations for flow of an elast ic fluid. A brief overview of these models is presented, with the major emp hasis being on the use of dimensionless parameters to define the range of t heir applicability for simple hydraulic systems. Guidelines for applicabili ty are presented in the form of graphs and equations. The effects of resist ance, inertia, and elasticity may vary in relative importance under differe nt circumstances. The present analysis provides a unified approach to repre sent each of these effects using a different parameter.