Abstarct: Pipe installation is of vital importance in water networks, irrigating networks, water power plants, nuclear power plants and industrial facilities. But rapid valve closure, sudden pump and turbin failure will cause massive changes in pressure of liquid inside pipes. If a pipe network faces an unsteady flow, flow characteristics such as velocity and pressure will change rapidly which will cause considerable pressure changes at some points. If these changes lead to pressure decline under the vapor pressure, the liquid inside the pipe will evaporate and cause the column separation phenomenon. In this condition, standard water hammer equations wouldn’t be applicable. The purpose of current study was to investigate the liquid column separation phenomenon and describe different possible aspects for computational nodes. To achieve this goal, the definitions of water hammer and liquid column separation were disscused, and then the basic ruling equations of this phenomenon were expressed in different scenarios. After that, introducing method of characteristics and numerical integration of the basic equations, numerical GIVCM was provided. This method use analytical and numerical methods simultaneously for solving integral equations of the liquid column seperation and is applicable for certain types of pipes and also considers various reactions between water hammer areas, extended cavitation areas, intermediate cavities and marginal cavities. The flowchart of the computer program in MATLAB has been drawn which displays different possible scenarios in computational sections simply. The pressure diagrams of software in three computational nodes for different initial velocities presented and compared with experimental results. GIVCM is a combinatorial model and because the assumed physical model is closer to real physics of the phenomenon, the results are more realistic and reliable. The results showed that this model can predict liquid column separation phenomenon very well, especially in two first peaks. With time, the timing of pressure calculations differs and cause errors in program. One of most important and affecting factors, is the assumption of steady friction in primary models. So it is suggested that the influences of nonsteady friction will be considered in future models.