Abstract
Based on an analogy to the Colebrook-White equation, a technique has been developed to allow polymer-solution extrapolation or “scaling” from one pipe size to another at constant values of ΔB. Each experimental data point can be transferred to a new pipe size by a simple, pocket-calculator method which preserves the experimental value of ΔB exactly. Thus scaling can be easily accomplished, without resorting to iteration or graphical techniques. The “negative-roughness” idea can also explain the loss of ΔB or drag reduction with increasing flow velocity.
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Abbreviations
- A, B :
-
constants in velocity profile equation
- ΔB :
-
constants corresponding to roughness (actual or negative)
- D :
-
pipe diameter, m
- k s :
-
height of sand-type roughness, m
- N :
-
nondimensional negative roughness parameter
- Re :
-
Reynolds number, UD/v
- U :
-
average velocity in pipe, m/sec
- u + :
-
local velocity in pipe, nondimensionalized with u *
- u * :
-
friction velocity, m/sec
- y :
-
radial distance from pipe wall, m
- y + :
-
nondimensional distance from wall, yu */ν
- λ :
-
Darcy friction factor
- v :
-
kinematic viscosity, m2/sec
- 1:
-
experimental data
- 2:
-
predicted
References
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Hoyt, J.W. “Negative roughness” and polymer drag reduction. Experiments in Fluids 11, 142–146 (1991). https://doi.org/10.1007/BF00190290
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DOI: https://doi.org/10.1007/BF00190290