One of the basic questions one need to answer is why we do study fluid mechanics? The answer to this question is simply
because in our world other than solids the rest is fluid. Atmosphere, Ocean, air , water, blood, oil, paint , gasoline are all examples of fluid.
The fluid motion is affected by the temperature difference. Also, motion of fluid affects energy transfer. It is important to understand these problems and to be able to predict fluid motion and energy transfer.