- I can describe factors affecting laminar flow, and explain how the design of an item or organism responds to these factors.
Fluid Dynamics - Fluid dynamics is the study of the factors that affect fluids in motion.
- Computational fluid dynamics can simulate the flow of air around a vehicle.
- As a fluid flows, the forces of attraction between the molecules cause internal friction, or resistance to the flow.
- Some fluids have more resistance than others.
Viscosity - The resistance of a fluid to flow is called its viscosity.
- Water has a low viscosity. Syrup has a higher viscosity.
Temperature Dependence - As temperature increases, the viscosity of a liquid generally decreases because the particles of the liquid have more energy and flow more easily.
- However, gases generally increase in viscosity as the particles collide more often making it more difficult for them to flow in one direction.
- Choosing the right oil viscosity grade for your vehicle requires consideration of the temperatures in which your vehicle will be operating.
External Friction - As fluids flow, their particles also interact with their surroundings and experience external friction.
- In a pipe the water flowing close to the sides is almost not moving while the water in the middle of the pipe can be moving quickly.
Laminar Flow - If the speed of a flow is slow and adjacent regions flow smoothly over one another, the flow is called laminar flow.
- This term can also be applied to air flow over a smooth object.
Eddies - Laminar flow is difficult to achieve because as the fluid flows past the object, the flow becomes irregular, resulting in whirls called eddies or vortices.
Turbulent Flow - Eddies are common in turbulent flow, a fluid flow with a disturbance that resists the fluid’s motion.
Turbulent Flow - Eddies are common in turbulent flow, a fluid flow with a disturbance that resists the fluid’s motion.
- Turbulent flow decreases kinetic energy as some of the energy is converted into thermal and sound energy.
Velocity - Turbulence increases with the velocity of the fluid.
- One mechanism of reducing turbulence in liquids is introducing small amounts of liquid plastic.
- Blood flow in arteries is typically turbulent. The introduction of liquid plastic into the bloodstream can help people who have problems with blood flow.
Turbulence and Design - Engineers consider the effects of turbulence when designing structures.
- For example, high rise buildings can direct strong gusts of air down to street level.
- The circular podium between the towers of Toronto City Hall was placed there to reduce winds.
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