GATE 2026 CH – Question 60
Consider a two-dimensional, steady, laminar flow of an incompressible fluid with zero pressure gradient, over a thin horizontal flat plate of length 2 m. The free stream velocity is 1 m s$^{-1}$. A boundary layer thickness of 1 mm is observed at a distance of 0.25 m from the leading edge of the plate. At 1 m from the leading edge, the boundary layer thickness (in mm) is _________ (rounded off to the nearest integer).
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Correct answer: 2
Explanation
For laminar flow over a flat plate (Blasius), the boundary layer thickness grows as $\delta \propto \sqrt{x}$. So $\delta_{1\,m} = 1 \times \sqrt{\frac{1}{0.25}} = 2$ mm.