Friction factor in a laminar flow through a pipeline is given by ______.
1
\(\frac{{32}}{{{{\mathop{\rm R}\nolimits} _e}}}\)
2
\(\frac{{64}}{{{{\mathop{\rm R}\nolimits} _e}}}\)
3
\(\frac{{16}}{{{{\mathop{\rm R}\nolimits} _e}}}\)
4
\(\frac{{128}}{{{{\mathop{\rm R}\nolimits} _e}}}\)