Question

The thickness of the turbulent boundary layer in case of a flat plate parallel to fluid flow is proportional to

• A. Square root of the distance from the leading edge
• B. (4/5)th power of the distance from the leading edge
• C. (1/5)th power of the distance from the leading edge
• D. distance from the leading edge

Answer 1

The correct option is B (4/5)th power of the distance from the leading edge

According to Blassius Experiment,
(For turbulent flow)

$\frac{\delta }{x}\propto \frac{1}{(R{e}_x{)}^{1/5}}$

$\frac{\delta }{x}\propto \frac{1}{{\left(\frac{\rho Ux}{\mu }\right)}^{1/5}}$

$\delta \propto x^{1-1/5}\delta \propto x^{4/5}$