Definition
The branch of physics that studies how fluids -- liquids and gases -- behave at rest and in motion, and how they interact with the surfaces they flow around or through.
Plain English
The science of how liquids and gases move and how they push on the things they touch.
Context Anchor
Seen in discussions of aerodynamics, aircraft systems, fuel, oil, brakes, and any place air or liquid movement affects the airplane.
Derivation
From Latin fluidus (flowing) and Greek mechanikos (relating to machines or movement). In aviation, the term covers both air flowing over an aircraft and fluids moving through its systems -- because the same physical laws govern both.
Why Pilots Care
Understanding fluid mechanics explains lift, drag, and thrust, allowing pilots to predict how the aircraft will respond in flight.
Grounding Statement
When air moves around a wing or oil moves through an engine, fluid mechanics describes what is happening.
Intuition Check
Do not read fluid as “liquid only.” In fluid mechanics, a fluid is anything that flows, including air.
Example Sentence 1
Lift, drag, and propeller thrust are all explained by the principles of fluid mechanics.
Example Sentence 2
Maintenance manuals refer to fluid mechanics when explaining fuel flow through the aircraft system.