Question

The ratio of the coeffecient of friction drag in laminar boundary layer compared to that in turbulent boundary layer is proportional to

• A. $R_L^{1/2}$
• B. $R_L^{1/5}$
• C. $R_L^{3/10}$
• D. $R_L^{-3/10}$

Answer 1

The correct option is D $R_L^{-3/10}$

$Laminarboundarylayer,{\overline{C}}_{f_L}=\frac{1.328}{R{e}_L}$

$Turbulentboundarylayer,{\overline{C}}_{f_r}=\frac{0.074}{R{e}_L^{1/5}}\therefore \frac{{\overline{C}}_{f_L}}{{\overline{C}}_{f_r}}=17.95R{e}_L^{-3/10}$