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Homework Help: Fluid Mechanics Open Channel Problem

  1. Apr 28, 2012 #1
    The problem: A canal cut in rock (n= 0.030) is a trapezoidal in section with a bottom width of 6.10m and the side slopes of 1 on 1. The allowable average velocity is 0.76 m/s. What slope will produce 5.66 m^3/s? The books answer is 0.000675

    from the mannings equation

    V=(1.486/n)R^2/3 x S^1/2 i get... 0.76=(1.486/0.030)? im confused on where to go
  2. jcsd
  3. Apr 29, 2012 #2
    Use of the Manning formula necessitates knowing the slope. But that is what is sought. So how did you do justify you did?

    Start out by determining the area of the open channel. Then use the Manning formula to determine the slope.
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