Non-Newtonian Fluids
Applied Science: BTEC Level 3 National Extended Diploma, topic 4.11.6
Non-Newtonian Fluid Flow
Non-newtonian fluids are fluids have interesting properties and behave differently to fluids you may be familiar with.
Newtonian fluids
- Newtonian fluids have a constant viscosity that is independent of the change in stress applied to the fluid over a period of time.
- Most fluids you are familiar with are newtonian, like water.
- Water has a constant viscosity and flows in a predictable manner.
Non-newtonian fluids
- Non-newtonian fluids do not have a single, constant viscosity throughout the fluid.
- The viscosity of a non-newtonian fluid depends on the force (and therefore stress) applied to the object.
Cornstarch solution
- You can easily make your own non-newtonian fluid by combining cornstarch and water.
- The resulting slime has a viscosity that depends on the force you apply to it.
- If you forcefully push the slime with your fingers, the viscosity is so high it almost feels solid.
- If you gently scoop the slime, it flows through your hands like cake batter!
Ketchup
- Another example of a non-newtonian fluid is ketchup.
- Ketchup is notoriously hard to dispense from a glass bottle.
- Ketchup flows more smoothly out of the bottle after applying a force to the upturned end.
- This is because the viscosity of the ketchup is decreased by applying the force to it.
Test yourself on Non-Newtonian Fluids
What happens to the viscosity of ketchup when you apply a force to the bottle?