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# Fluid Dynamics

### Vocabulary and equations for Fluid Dynamics

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

What is the symbol commonly used for Specific Weight? | Gamma |

What is the formula for Specific Weight? | Weight per unit Volume |

What is the symbol commonly used for Density? | Rho |

What are the units for specific gravity? | It is unitless |

What does Density measure? | Mass per unit Volume |

What is the formula for Specific Gravity? | Density of material over Density of water @ 4 degrees Celsius (1000 kg/m^3 in SI) |

What are the three most common systems of measurement? | SI, BG, and EE |

How is one Newton of force measured in SI? | One Newton of force is the force required to move one kilogram of mass at one meter per second squared of acceleration. |

How is one pound of force measured in EE? | One pound of force is the force necessary to move one pound of mass at 32.2 ft per second squared of acceleration, divided by the gravitation constant of 32.2. |

How is Weight Flow Rate (W dot) defined? | Weight per unit time, or Q dot*Gamma |

How is Mass Flow Rate (M dot) defined? | Mass per unit time, or Q dot*Rho |

How are W dot and M dot related? | W dot = M dot*g |

What is the Ideal Gas Law? | p=Rho*R(Gas Constant)*T(In degrees Rankin) |

What is an Iso-thermal process? | One in which there is no change in temperature. |

What is the pressure ratio formula for an Iso-thermal process? | (P1/Rho1)=(P2/Rho2) |

What is an Isentropic process? | A process which is both reversible and Adiabatic. |

What is an Adiabatic process? | One in which there is no heat (Q) lost outside the system. (A.K.A. no friction is present) |

What is the pressure ratio formula for an Isentropic process? | (P1/(Rho1^k))=(P2/(Rho2^k)) |

What is Standard Atmospheric Pressure? | 14.7 |

What is the formula to derive the speed of sound in a gas? | c=Root((k*P)/Rho) or (Perfect gas) c=Root(k*R*T) |

How is Mach number derived? | Speed of object divided by the speed of sound in that medium. |

What is the Bulk Modulus of Elasticity (Ev)? | dP/(-dV/V) or "The amount of pressure necessary to change V by an amount equal to dV" Units are in units of pressure (pascal, psi, etc...) |

What is the formula to derive the speed of sound in a liquid? | c=root(dP/dRho)=root(Ev/Rho) |

What is vapor pressure? | The pressure at which a liquid volatilizes. |

What is a venturi tube? | A choked tube which takes advantage of a liquids vapor pressure to volatilize it. |

What is the formula for determining velocity of an incompressible flow through a tube? | P + (1/2)V^2 = A constant |

When is a flow considered to be incompressible? | At M<=0.3 |

What is cavitation? | When bubbles burst due to being brought above and below vapor pressure. |

Where is the no slip condition found? | On the walls of a pipe is one location. |

What types of fluids does a no slip condition hold true for? | Viscid flows. |

What is Newtons Law of Viscosity? | Tau=Mu(dU/dy) U is pipe flow velocity and y is the pipe bore width. |

What is Tau in Newtons Law of Viscosity? | Shear stress (Tangential force per unit area) |

What does the symbol Mu stand for? | Dynamic Viscosity |

What does the symbol Nu stand for? | Kinematic Viscosity |

How are dynamic and kinematic viscosities related? | Mu=Nu*Rho |

What is the Sutherland Equation? | Mu=(CT^(3/2))/(T+S) Where T is absolute temperature. C and S are fluid dependent constants. |

Is the Sutherland equation used for fluids or gasses? | Gasses |

What is Andrades equation? | Mu=D*e^(B/T) Where D and B are constants and T is measured in absolute temperatures. |

Is Andrades equation used for fluids or gasses? | Liquids |

What is the relationship between temperature and Mu in gases? | As temperature rises, so does Mu. |

What is the relationship between temperature and Mu in liquids? | As temperature rises, Mu falls. |

What is the formula for Reynolds number? | R=(Rho*V*D)/Mu V is mean velocity and D is a length scale. An alternate formula is (V*D)/Nu, as Nu=Mu/Rho |

What are some assumptions made in the static pressure equation used in class? | Assumed inviscid flow, assumed homogeneous fluid, assumed zero Tau, assumed zero acceleration, assumed incompressible (Gamma is constant). |

What is the Hydrostatic Pressure Distribution equation? | P1-P2=Gamma*H |

What is the formula for pressure gage from surface? | P=Gamma*H |

How is pressure head defined? | (P1-P2)/Gamma=H |

What is standard atmospheric pressure and temperature in B.G. units? | 14.7 psi and 59 degrees F. |

If a question doesn't specify pressure or temperature, should we assume one? | Yes, use STP. |

What is the definition of a Newtonian fluid as used in this course? | Viscosity is constant. |

What is a boundary layer? | The layer next to a surface where the no-slip condition is created. |

When talking about the boundary layer, what is the height of the boundary layer referred to? | Delta. |

What is the boundary layer caused by? (Simplified) | Viscosity |

What is the symbol used for Dynamic Viscosity? | Mu |

What is the symbol used for Kinematic Viscosity? | Nu |

How are Dynamic and Kinematic viscosities related? | Mu=Nu*Rho |

What are the units in SI for Shear Stress? | Newton/m^2 |

How many feet are in a meter? | 1m=3.28ft |

What is the definition for Kinematic Viscosity? | Tau*dY/dU or Nu*Rho |

How are Specific Weight and Density related mathematically? | Gamm=Rho*g |