Fluid mechanics is a discipline of physics that studies the nature as well as behavioral patterns of fluid flow. Fluid dynamics is a subfield of fluid mechanics that focuses on fluid flow.
Fluid dynamics is the computation of numerous fluid parameters as functions of a particular time and place, such as velocity profile, tension, density, as well as warmth.
Example: Water flowing through some kind of channel, pipeline, or across a surface.
Therefore, fluid dynamics provides a systematic framework for the practical disciplines that rely on flow meters.