Exercise 14

  1. Calculate the hydraulic radius of the circular pipe and trapezoidal concrete channel shown below. Assume the concrete channel is symmetric and the length units are meters.
Figure showing hydraulic radius
  1. If the flow is 0.005 m3/s, what is the mean velocity for each conveyance?
  2. What is the Reynolds number for each conveyance? Assume water temperature is 20o C.
    Hint: The kinematic viscosity [m2/s] is the ratio between the dynamic viscosity of a fluid [(1 Pascal-second) = 1 kilogram/(meter-second)] and the density of a fluid [kg/m3]. The SI unit of the kinematic viscosity is m2/s. Other units are:
    • 1 St (Stoke) = 1 cm2/s = 10−4 m2/s;
    • 1 cSt (centiStoke) = 1 mm2/s = 10−6m2/s; and
    • Water at 20 °C has a kinematic viscosity of about 1 cSt.
  1. Is flow laminar or turbulent in each conveyance?
  2. If the flow is 0.005 m3/s, what is the mean velocity for each conveyance?

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Introduction to Karst Aquifers Copyright © 2022 by Eve L. Kuniansky, Charles J. Taylor, and Frederick Paillet. All Rights Reserved.