Fluid Flow is dealt with by fluid dynamics and is a part of fluid mechanics. Fluids include gases and liquids. Fluid in motion is called Fluid Flow.
Study of fluids in motion is more complex, and is called fluid dynamics. There are two approaches in the study of moving fluids. One approach is to follow individual particles of the fluid and set the position of each particle as a function of time. This method is extremely complex and difficult. This method was developed by J.L. Lagrange. The second approach is to specify the density, pressure and velocity of the fluid at each point in space at each instant of time. This approach is more convenient and more usual. This method was developed by L. Euler.