Computational fluid dynamics or CFD is science of predicting fluid flow. Claude Louis Marie Henry Navier (1785-1836) and George Gabriel Stokes (1819-1903) introduced viscous transport into the Euler equations, which resulted in the Navier-Stokes equation. This forms the basis of modern day CFD. CFD can provide detailed information about what is happening in a process where fluid is in motion. The technique is very powerful and spans a wide range of industrial and non-industrial applications. Present day- recent advances in computing power, advanced computer graphics and robust solvers make CFD a cost effective engineering design tool. CFD is very effective design tool especially turbo machinery components (Pump Impeller, Volute, Diffuser, Return vane, Hydro Turbine runner, Spiral Casing, Guide vane, Draft tube, Compressor, Steam Turbine, Gas Turbine) which is used by R & D department of all modern day turbo machinery manufacturers of the world. Also our methodology of CFD which is used for product development is validated with experimental result.