Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.

Normal Size Small Size show me how

Normal Size Small Size show me how

# Fluids: Chapter 9

Question | Answer |
---|---|

external flows | flows where an object is completely surrounded by the fluid |

upstream velocity | U - velocity of a fluid flowing past a stationary body |

streamlined bodies | bodies that have little effect on the surrounding fluid |

blunt bodies | bodies that have a lot of effect on the surrounding fluid |

drag | the resultant force from pressure and shear stress in the direction of the upstream velocity |

lift | the resultant force from pressure and shear stress in the direction normal to the upstream velocity |

lift coefficient | Cl = lift/(.5*rho*U^2*A) |

drag coefficient | Cd = drag/(.5*rho*U^2*A) |

low Reynolds number flows | the viscous effects are felt far from the object in all directions (streamlines deflected considerably) |

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 |

wage region | the region behind the object |

boundary layer | the region in which the fluid velocity changes from the upstream value to zero velocity |

flow separation | when nonstreamlined bodies are in flows with high Reynolds numbers- the flow separates from the body |

laminar boundary layer | near the leading edge of a flat plate with high Re, particles distort regularly |

turbulent boundary layer | some distance downstream from the leading edge, particles greatly distorted |

boundary layer thickness | that distance from the plate at which the fluid velocity is within some arbitrary value of the upstream velocity |

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 |

boundary layer momentum thickness | theta. often used when determining the drag on an object |

free-stream velocity | the fluid velocity at the edge of the boundary layer |

the cause of the pressure gradient in the boundary layer? | variation in the free-stream velocity |

friction drag | that part of the drag that is due directly to the shear stress on the object |

pressure drag | that part of the drag that is due directly to the pressure on the object |

Created by:
1480170078