Abstarct: Prevention of cavitation is so important in internal flows such as valves and pumps and some external flows such as hydro power plants. On the other hand, this phenomenon has advantages in some external flows. Its formation around underwater projectile reduces the frictional drag force due to the reduction of viscosity in the vapor phase. This is one of the main reasons for the use of natural or artificial cavitation of underwater projectiles. The high cost of laboratory works and time consuming to view this phenomenon, cause the increasing of numerical superiority in this field. This thesis presents the estimation of destructive cavitation phenomenon study in a numerical method. Quantitative measure which is called cavitation corrosion rate has been investigated to estimate the destructive impact of cavitation phenomenon. After defining the cavitation phenomenon, the governing fundamental equations are given and then existing model for analysis and numerical solutions for this phenomenon have introduced. In numerical study, first of all, cavitation corrosion rate has introduced, then by considering three states as fixed velocity, variable velocity and the transfer rate of corrosion mode and by entering code numbers using the C++ language program under Linux, numerical solutions have proposed which are capable of simulating and cavitation corrosion rate quantity calculation. The Open Foam software is used to run the numerical codes. A nozzle geometry is chosen which is fitted with the experimental results. In order to calculate the quantity of cavitation corrosion rate in all states, two kinds of mextals, steel and aluminum, are used in different pressures. In a fixed velocity and variable velocity cases, the numerical corrosion rate is obtained and the achieved results are compared with experimental results. By using the transfer of corrosion principle, cavitation corrosion rate is calculated. Finally, the average relative error percentage for each of three states is calculated. baxsed on the lowest average relative error percentage of transfer of corrosion principle compared with other cases, in order to obtain cavitation corrosion rate, using transfer of corrosion principle is recommended. Two other approaches require excessive computation memory, unavailability of mextal for precise corrosion experiment, shortage of laboratory equipped with corrosion test equipment and other factors. As a result, the transfer of corrosion principle approach is recommended.