def f_tr_Colebrook(Re_D, ɛ, D):
def cb(f, Re_D, ɛ, D):<EOL><INDENT>"""<STR_LIT>"""<EOL>term1 = ɛ / D / <NUM_LIT><EOL>term2 = <NUM_LIT> / Re_D / sqrt(f)<EOL>return -<NUM_LIT:2> * log10(term1 + term2) - <NUM_LIT:1> / sqrt(f)<EOL><DEDENT>return root(cb, <NUM_LIT>, args=(Re_D, ɛ, D)).x[<NUM_LIT:0>]<EOL>
Calculate the friction factor of turbulent flow (t) a rough duct (r) for
the provided conditions with Colebrook's equation.

:param Re_D: Reynolds number for the specified hydraulic diameter.
:param ɛ: [m] Surface roughness.
:param D: [m] Duct hydraulic diameter.
:return: Friction factor.