The phenomena of cavitation are very important in a variety of industrial processes and engineering applications. Therefore, the simulation of cavitating flows in high-pressure devices has become a very challenging topic in the fields of computational fluid dynamics. This paper reports recent developments and application studies on computational fluid dynamic (CFD) for cavitating flows inside a circular orifice. A new cavitation model named as full cavitation model is employed for simulations. In this model, the working fluid is assumed to be a mixture of three phases (liquid, vapor and non-condensable gas). In all simulations, finite volume scheme is used, and SIMPLEC algorithm is utilized for the pressure and velocity linkage. Upwind scheme is used to model convective fluxes and other transport equations. Turbulence effects are considered using the k-ε model. Measurements are performed at various inlet pressures and a fixed outlet pressure. The results are compared with the published experimental data and have an acceptable accuracy. It is observed that increasing inlet pressure has considerable influence on the inception of cavitation and development of cavitation. The inception of cavitation is observed at inlet pressure of 225000 Pa and cavitation zone grows near the wall with increasing of inlet pressure. The simulation shows that if the pressure is high enough, the cavitation cloud grows and reaches the nozzle outlet, resulting in a so-called hydraulic flip.