The thickness of a laminar boundary layer $(\delta)$ over a flat plate is, $\frac{\delta}{x}=\frac{5.2}{\sqrt{\operatorname{Re}_{x}}},$ where $x$ is measured from the leading edge along the length of the plate. The velocity profile within the boundary layer is idealized as varying linearly with $y$. For freestream velocity of $3 \mathrm{~m} / \mathrm{s}$ and kinematic viscosity of $1.5 \times 10^{-5} \mathrm{~m}^{2} / \mathrm{s}$, the displacement thickness at $0.5 \mathrm{~m}$ from the leading edge is__________ $\mathrm{mm}$ (round

off to two decimal places).

The thickness of a laminar boundary layer $(\delta)$ over a flat plate is, $\frac{\delta}{x}=\frac{5.2}{\sqrt{\operatorname{Re}_{x}}},$ where $x$ is measured from the leading edge along the length of the plate. The velocity profile within the boundary layer is idealized as varying linearly with $y$. For freestream velocity of $3 \mathrm{~m} / \mathrm{s}$ and kinematic viscosity of $1.5 \times 10^{-5} \mathrm{~m}^{2} / \mathrm{s}$, the displacement thickness at $0.5 \mathrm{~m}$ from the leading edge is__________ $\mathrm{mm}$ (round

off to two decimal places).

127