Write short note on the development of boundary layer over a flat surface.

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written 2.6 years ago by

Chandan15 • 300

When a fluid flows past a flat plate, the velocity at leading edge is zero and retardation of fluid increases as more and more of the plate is exposed to flow. Hence, boundary layer thickness increase as distance from leading edge increases.
Upto certain distance from the leading edge, flow in boundary layer is laminar irrespective of the fact that flow of approaching stream is laminar or turbulent.
Change of Boundary layer from Laminar to Turbulent is affected by : (a) Roughness of Plate (b) Plate Curvature (c) Pressure Gradient (d) Intensity and scale of turbulence
Transition of boundary layer from laminar to turbulent is assumed to occur at $R e_{x}=5 \times 10^{5}($ for flat plate $)$ $$ \operatorname{Re}_{x}=\frac{U_{\infty} x}{v} $$ where, $x=$ distance from leading edge
At a particular value of $x$, boundary layer thickness decreases as velocity increases. - As kinematic viscosity increases, boundary layer thickness increases. - Thus, for a particular $x$-value, as Re increases, boundary layer thickness decreases

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