Abstarct: In the Pipeline networks including water supply system, industrial plants and hydropower and nuclear power stations sudden closure of a valve or shut down of a pump or turbine cause the steady fluid flow to change to unsteady state. The formation of the unsteady flow in the network cause the flow velocity and pressure to start changing and as the time goes on the pressure varies extremely high in some points of the network. In the case of decreasing the pressure to the vapor pressure of the fluid at a certain point of the network, the state of fluid in the pipe will change to vapor state, causing liquid column separation. The fluid mechanics phenomenon is manifested as a localized vapor cavity separating the fluid column or distributed vaporous cavitations region which may extend over long sections of the pipe. The collapse of a discrete vapor cavity or the movement of the shock wave front into a distributed vaporous mixture reestablishes the liquid phase. In the case of liquid column separation, the standard water hammer equations are not applicable and depending on the state of the transient flow i.e. vapor cavity or distributed vaporous cavitation, other equations will be used. For analysis and simulation of these phenomena, different models baxsed on finite difference method and method of characteristics including Discrete Single Cavity, Discrete Vapor Cavity, Discrete Generalized Cavity and generalized Interface Vaporous Cavitation models have been introduced. In this study, various types of cavitations along with detailed mathematical and numerical models for transient flow have been discussed and new suggestions for improving the numerical methods are introduced.