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Week 3: Fluids: Substances that flow, that applies to liquids & gases …

- - - - Varies with weather & elevation
      - 1 atm = 1.013 x 10^5 Pa
    - - (in static fluids) Pstatic = pfluid (density of fluid) x gh
      - Fluid statics: Study of fluids at rest
    - - P1 (N1/A1) = P2 (N2/A2)
      - Insert pic of U-tube from slides
        
        At h3, both sides of the tube are exposed to the air, so both sides must be at atmospheric pressure.
        
        At h2, the left side of the tube is still at atmospheric pressure, but the right side of the tube is NOT, it is at some depth with the blue liquid. Hence pressure at h2 = atmospheric pressure + Pressure due to weight of blue liquid above h2.
        
        At h1, similar to h2, the pressure of h1 = atmospheric pressure + pressure due to the weight of blu liquid above h1
    - - (displaced .. object) When submerged and also encounter upthrust force = weight of fluid displaced
        
        (weight .. displaced) = Pressure (pgh) x Area (A)
  - - - Where
        
        p = density of fluid (kg/m^3) ; v = velocity of fluid, (m/s)
        
        L = characteristic linear dimension (m)
        
        "u" = dynamic viscosity of fluid, Pa.s or N.s/ m2 or kg/(m.s)
      - Low values of Re: Laminar flow
        
        Needs Re=2000 to change into
      - Higher values of Re: Turbulent flow
- - - - Normally occurs when the speed of fluid is too high, in combination with other factors
      - NO steady flow with the flow pattern changing constantly
  - - - Av (at point 1) = Av (at point 2) with equal mass flow at both points
      - Av (Cross-sectional Area x Velocity): Volumetric flow rate in m^3/s
        
        Found by Delta volume (m^3) / Delta time (s)
      - with constant Av
        
        When an incompressible fluid (eg water) flows steadily via a pipe, the SAME amount of fluid must pass through a part of the pipe in any given amount of time.
        
        Smaller A, larger v for constant Av