Fluid mechanics

 is the branch of physics that studies the mechanics of fluids (liquids, gases, and plasmas) and the forces on them.

Quotes

 * If 99.99% of the universe is in the plasma state then for the remaining 0.01% must we learn a whole discipline of Fluid Mechanics or Hydrodynamics? The answer is No! More often than not, hydrodynamics provides a first level description of an astrophysical fluid.


 * Fluid mechanics is a part of applied mathematics, of physics, of many branches of engineering, certainly civil, mechanical, chemical, and aeronautical engineering, and of naval architecture and geophysics, with astrophysics and biological and physiological fluid dynamics to be added.


 * Curiosity about at least two of the branches of fluid mechanics and their applications has a long and distinguished history, for in the Proverbs of Solomon the son of David, king of Israel, it was stated in the words of Agur the son of Jakeh that "There be three things which are too wonderful for me, yea four which I know not," of which two were "The way of an eagle in the air" and "The way of a ship in the midst of the sea," which I take to be questions of aerodynamics and naval architecture, questions that concern us still.


 * One wonders if the foundations of fluid mechanics or gas dynamics would ever have been secured if Euler or Boltzmann had justified their work to themselves in terms of its contribution to the design of jet aircraft.