This study performed the numerical simulation for the internal nozzle flows including cavitation phenomena using the automated body-fitted grid generator and the multi-fluid model. The effect of grid refinement and the validation of multi-fluid model were investigated using four computational meshes under two test cases. The mesh 3 was selected as the optimum which can reduce the computational time and have good prediction ability to simulate the cavitation region simultaneously. In addition, the computed results using multi-fluid model were compared with the reference experimental observations and numerical simulation results using homogeneous equilibrium model. From the distribution of volume fraction and velocity field, the multi-fluid model predicted the internal nozzle flows well when the liquid quality parameters were chosen as 1.0×1012 for initial number density and 25 ㎛ for bubble diameter.