CalebBell / fluids

87%

push

github

Fix Papaevangelo_2010 friction factor: log10 not natural log in numerator (#97)

* Fix Papaevangelo_2010: use log10, not natural log, in the numerator

The numerator term (7 - log Re)^4 used math.log (natural log) while the
denominator and the source correlation use log10. Over the method's
registered range (Re 1e4-1e7, eD 1e-5-1e-3) this gave errors up to ~260%
versus Colebrook and negative friction factors above Re~3e6.

Switch the numerator to log10 (max error drops to ~0.6%) and fix the
docstring formula. The doctest and unit-test reference values were baked
from the buggy output; recompute them. Add a range sweep asserting the
correlation stays positive and within 1% of Colebrook across its domain.

* Drop tol=0 from the Colebrook reference so the test doesn't need mpmath

4092 of 5290 branches covered (77.35%)

1 of 1 new or added line in 1 file covered. (100.0%)

12455 of 14278 relevant lines covered (87.23%)

22.32 hits per line