Laufer [5] measured the following data for mean velocity near the wall in fully developed turbulent pipe flow at \(R e_{U}=50,000(U=9.8 \mathrm{ft} / \mathrm{s}\) and \(R=4.86\) in. \()\) in air:

Plot the data and obtain the best-fit slope, \(d \bar{u} / d y\). Use this to estimate the wall shear stress from \(\tau_{w}=\mu d \bar{u} / d y\). Compare this value to that obtained using the friction factor \(f\) computed using

(a) the Colebrook formula (Eq. 8.37), and

(b) the Blasius correlation (Eq. 8.38).

Transcribed Image Text:

u/U 0.343 0.318 0.300 0.264 0.228 0.221 0.179 0.152 0.140 y/R 0.0082 0.0075 0.0071 0.0061 0.0055 0.0051 0.0041 0.0034 0.0030