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# Fluids Vocab Quiz

Term | Definition |
---|---|

Solid vs. Fluid | Solids reach new equilibrium with applied shear while fluids constantly deform creating fluid motion. |

Liquid | A fluid with strong cohesive forces that can form a free surface and retains its volume |

Gas | A fluid with negligible cohesive forces that fills its available volume and can't form free surfaces. |

Molicule | Two or more atoms bonded together |

Particle | A part of somthing |

Continuum vs. Rarified | Continuum is most cases Rarified if pressure so low that mean free path and molecular spacing is greater than the space |

Inviscid | An ideal fluid with zero viscosity |

Temperature | A measure of average thermal energy in a defined volume |

Pressure | Force per unit area |

Static Pressure | Pressure in the fluid irregardless of motion |

Gauge Pressure | Value of pressure above atmospheric pressure found by subtracting atmospheric from fluid pressure. Also the value on a relative gauge |

Vacuum Pressure | Negative value of gauge pressure |

Absolute/Total Pressure | The total value of the fluid pressure including atmospheric pressure |

Vapor Pressure | Pressure at which a liquid boils at a specified temperature |

Dynamic Pressure | Kinetic energy per unit volume of a fluid |

Plasma | An ionized gas |

Boundary Layer | A layer above a surface where a flow characteristic is effected by the surface |

Fields (force and Properties) | A directional field |

Rotation vs. Irrotational | Rotational flow requires a local change in angular velocity. |

Buoyancy | The upward force on a submerged object due to pressure differentials |

Scalar, Vector, Tensor | Directional(value of 1), value with scale and direction, a geometric relation between a number of vectors or scalars |

Surface tension | The imbalance of intermolecular forces at the surface that cause fluids to cling to each other at a boundary and retard expansion. |

Wetting vs. Non-Wetting (hydrophilic vs hydrophobic) | has to do with contact angle cause by surface tension. Wetting greater than 90 non-wetting less than 90 |

Specific Gravity | Compares density of a fluid to that of a known fluid usually water at 4 degrees C or air for gasses |

Cavitation | liquid flow goes below vapor pressure due to flow phenomenon which produce small vapor bubbles |

Boil/Vaporize | A phase change from liquid to solid |

Viscosity (viscous vs inviscid) | A measure of a fluids resistance to flow based on a measure of its strain rate under an applied shear. |

Kinematic Viscosity | Diffusivity of momentum |

Newtonian Fluid | a fluid with a linear relationship between shear stress and strain rate |

Dilatant vs. pseudo plastic (shear thickening vs shear thinning) | Dilatant increases viscosity with increased strain while pseudo plastics lower their viscosity. |

Isothermal | A process that occurs at constant temperature |

Adiabatic | Without heat transfer |

No-slip Boundary condition vs Slip | Means that the fluid in contact with a surface experiences no slip. Slip occurs in rarefied gasses. |

Reynolds Number | A ratio of inertia over viscus forces that characterizes flow behavior |

Langrangian vs. Eulerian | Langrangian moves with the flow while Eulerian watches the flow |

Compressible vs. Incompressable | Ability to experience changes in density vs. constant density |

Vorticity and angular velocity | Local changes in angular position |

Internal vs. External Flow | Bounded vs. unbounded flow |