polykin.transport.flow¤
fD_Haaland ¤
fD_Haaland(Re: float, er: float) -> float
Calculate the Darcy friction factor using Haaland's equation.
For turbulent flow, i.e., \(Re \gtrsim 2300\), the friction factor is given by the following explicit expression:
\[ \frac{1}{\sqrt{f}}= -1.8 \log \left[\left(\frac{\epsilon/D}{3.7}\right)^{1.11}
+ \frac{6.9}{Re} \right] \]
This equation is as accurate as Colebrook's but has the advantage of being explicit.
References
- Haaland, S. E. "Simple and Explicit Formulas for the Friction Factor in Turbulent Pipe Flow", ASME. J. Fluids Eng. March 1983; 105(1): 89-90.
PARAMETER | DESCRIPTION |
---|---|
Re
|
Reynolds number.
TYPE:
|
er
|
Relative pipe roughness, \(\epsilon/D\).
TYPE:
|
RETURNS | DESCRIPTION |
---|---|
float
|
Darcy friction factor. |
See also
fD_Colebrook
: alternative method.
Examples:
Calculate the friction factor for water flowing at 2 m/s through a PVC pipe with an internal diameter of 25 mm.
>>> from polykin.transport import fD_Haaland
>>> rho = 1e3 # kg/m³
>>> mu = 1e-3 # Pa·s
>>> D = 25e-3 # m
>>> v = 2. # m/s
>>> Re = rho*v*D/mu
>>> er = 0.0015/25 # from pipe table
>>> fD = fD_Haaland(Re, er)
>>> print(f"fD = {fD:.3f}")
fD = 0.021
Source code in src/polykin/transport/flow.py
319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 |
|