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Resistance in Fluid Systems. Mr. Andracke Principles of Technology. Daily Objectives . Each student will be able accurately complete the following: Understand and define the types of drag and its applications Define laminar and turbulent flow Explain viscosity and how it is measured. Drag.
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Resistance in Fluid Systems Mr. Andracke Principles of Technology
Daily Objectives • Each student will be able accurately complete the following: • Understand and define the types of drag and its applications • Define laminar and turbulent flow • Explain viscosity and how it is measured
Drag • What is Drag??
Drag • Drag is defined as the force found when a solid object moves through a fluid, also there is a force that opposes the motion. • Example: When an airplane moves through air. • What is another example of drag?
Understanding Drag • Thrust = Drag • Drag is an aerodynamic force that resists the motion of an object moving through a fluid.
Laminar Flow • Laminar or streamlined flow is a slow, smooth flow over a surface, in which the paths of individual particles do not cross. These particle follow theoretical layers of fluid. • Laminar Flow creates frictional drag • What is an example of Laminar Flow on an object?
Turbulent Flow • Turbulent flow is an irregular flow that is disrupted causing fluid to move in different directions. • Turbulence causes a wake behind a moving object. • Turbulent flow creates pressure drag • What is an example of Turbulent Flow on an object?
Frictional Drag • Frictional Drag is produced by the friction between successive or laminated layers of fluid, with increasing speed away from the surface. When does Frictional Drag take place?
Pressure Drag • The pressure difference found in turbulent flow causes a force to act on the object in the direction opposite its relative velocity. When does Pressure Drag take place?
Understanding Drag • Both Frictional and Pressure Drag increase as the speed of an object increases. • When turbulence is created, pressure drag increases more rapidly than friction drag.
Viscosity • What is Viscosity??
Viscosity • Friction between two solid surfaces causes a resistance to movement between the surfaces. • Viscosity is the property of a fluid that describes its internal friction.
Viscosity What are some items that might have a higher viscosity? A lower viscosity?
Viscosity • Different fluids resist motion differently, and therefore have different viscosities. • Gum and Molten Lava have high viscosities • Air and Water have a much lower viscosity
Review Questions • What is one type of drag and give an example? • What is the main difference between laminar and turbulent flow? • Explain viscosity and give an example.