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Homework Help: Did I calculate the boundary layer thickness correctly?

  1. Dec 8, 2013 #1
    1. The problem statement, all variables and given/known data
    A flat plate moves in water (20°C) in the direction of the plate at a speed of 1 m/s. What is the boundary layer thickness 0.1 meter downstream of the plate?


    2. Relevant equations
    Reynolds number:
    ##Re_x=\frac{xU_∞}{\nu}##

    Boundary layer thickness for laminar flow:
    ##\frac{\delta}{x}=\frac{5.0}{\sqrt{Re_x}}##


    3. The attempt at a solution
    Reynolds number is:
    ##Re_x=\frac{xU_∞}{\nu}=\frac{1m/s\cdot 0.1m}{9\cdot 10^{-7}}=1.1\cdot10^5##

    Boundary layer thickness:
    ##\frac{\delta}{x}=\frac{5.0}{\sqrt{Re_x}}=\frac{5.0}{\sqrt{1.1\cdot10^5}}=0.015##

    ##\frac{\delta}{x}=0.015⇔##

    ##\delta=0.015\cdot 0.1m=0.0015m=1.5mm##
     
  2. jcsd
  3. Dec 9, 2013 #2
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