Question

If x is the distance measured from the leading edge of a flat plate,then laminar boundary layer thickness varies as

• A. 1/x
• B. $x^{4/5}$
• C. $x^2$
• D. $x^{1/2}$

Answer 1

The correct option is D $x^{1/2}$

Boundary layer thickness,
$\delta =\frac{5x}{\sqrt{R}{e}_x}forlaminarboundarylayer$
$whereR{e}_x=\frac{Vx}{v}$
$\therefore \delta =\frac{5x}{\sqrt{Vx/v}}=\frac{5\sqrt{x}}{\sqrt{V/v}}$
$\delta \propto x^{1/2}$