Newtonian Fluid

What is Newtonian Fluid?

A fluid whose shear stress is directly proportional to the rate of shear, with a viscosity that stays constant no matter how fast or slow it's deformed. Water and air are both classic examples, which is why most introductory fluid mechanics gets to assume this simple, linear behaviour.

The five clues

Engineerdle #36 described Newtonian Fluid with five clues, revealed one at a time from hardest to most direct. Each clue points at a different property of the concept.

1. 01The 'well-behaved' category that most basic fluid mechanics assumes.
2. 02Its viscosity doesn't care how hard you're shearing it.
3. 03Water and air both belong to this tidy category.
4. 04Its stress-strain-rate relationship is a simple straight line through the origin.
5. 05A fluid whose shear stress is directly proportional to shear rate, with constant viscosity.

More Fluid Mechanics concepts

• Venturi EffectPuzzle #50
• ViscosityPuzzle #46
• Reynolds NumberPuzzle #41
• Non-Newtonian FluidPuzzle #31
• Pascal's LawPuzzle #13
• Archimedes' PrinciplePuzzle #8