In 1940's, Schultz-Grunow proposed that time-average value of friction factor, λ u,ta was similar to its corresponding steady state value, λ for the presence of gradual and slow oscillations in pulsatile flows. A recent approach was available for low frequency pulsatile flows through narrow channels in transitional and turbulent regimes by Zhuang et al, in 2016 and 2017. In this analysis; extensive experimental data of , in fully laminar and turbulent sinusoidal flow are processed in the measured time-average Reynolds number range of 1390 ≤ ≤ 60000 disregarding the transitional regime. The ranges of dimensionless frequency-Womersley number, √ ′ and oscillation amplitude, 1 are 2. 72 ≤ √ ′ ≤ 28 and 0.05 ≤ 1 ≤ 0.96 respectively. A