A numerical study has been performed to investigate some general features of the time-dependent dynamics of a square cylindrical liquid column during its relaxation and disintegration processes. A computer code based on VOF method has been developed to reveal the insight phenomena of the processes. Before using for present investigation, the code is validated by comparing the simulation result with the experimental data. It is found that the simulation result agrees well with the experiment and decided to use this code for the investigation of relaxation, disintegration and capillary instability of the liquid column. In present investigation the numeric illustrates the underlying physics during relaxation of the liquid cylinder, formation of capillary wave, its propagation and disintegration of liquid column. The investigation on the disintegration processes shows some significant differences from those predicted by conventional jet atomization theories. It can be observed that the formation of capillary wave is initiated by the surface tension on the sharp edge of the square end of the cylinder and the propagation of the wave occurs due to the effect of surface tension force on the motion of the fluid. The investigation reveals that before disintegration of the liquid, the capillary waves become unstable and the source of this instability is inherently developed by the system. (C) 2010 Elsevier Ltd. All rights reserved.