Fluids: Chapter 9
Quiz yourself by thinking what should be in
each of the black spaces below before clicking
on it to display the answer.
Help!
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| external flows | flows where an object is completely surrounded by the fluid
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| upstream velocity | U - velocity of a fluid flowing past a stationary body
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| streamlined bodies | bodies that have little effect on the surrounding fluid
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| blunt bodies | bodies that have a lot of effect on the surrounding fluid
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| drag | the resultant force from pressure and shear stress in the direction of the upstream velocity
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| lift | the resultant force from pressure and shear stress in the direction normal to the upstream velocity
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| lift coefficient | Cl = lift/(.5*rho*U^2*A)
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| drag coefficient | Cd = drag/(.5*rho*U^2*A)
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| low Reynolds number flows | the viscous effects are felt far from the object in all directions (streamlines deflected considerably)
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| large Reynolds number flows | flow is dominated by inertial effects and the viscous effects are negligible everywhere except in a region very close to the plate and in the relatively thin wake region behind the plate
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| wage region | the region behind the object
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| boundary layer | the region in which the fluid velocity changes from the upstream value to zero velocity
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| flow separation | when nonstreamlined bodies are in flows with high Reynolds numbers- the flow separates from the body
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| laminar boundary layer | near the leading edge of a flat plate with high Re, particles distort regularly
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| turbulent boundary layer | some distance downstream from the leading edge, particles greatly distorted
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| boundary layer thickness | that distance from the plate at which the fluid velocity is within some arbitrary value of the upstream velocity
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| displacement thickness | represents the amount that the thickness of the body must be increased so that the fictitious uniform inviscid flow has the same mass flowrate properties as the actual viscous flow
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| boundary layer momentum thickness | theta. often used when determining the drag on an object
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| free-stream velocity | the fluid velocity at the edge of the boundary layer
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| the cause of the pressure gradient in the boundary layer? | variation in the free-stream velocity
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| friction drag | that part of the drag that is due directly to the shear stress on the object
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| pressure drag | that part of the drag that is due directly to the pressure on the object
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Or sort by any of the columns using the down arrow next to any column heading.
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