Project ForgeFluid Mechanics
Bernoulli's Equation & Flow
GATE 2018
Medium
The viscous laminar flow of air over a flat plate results in the formation of a boundary layer. The boundary layer thickness at the end of the plate of length L is δL. When the plate length is increased to twice its original length, the percentage change in laminar boundary layer thickness at the end of the plate (with respect to δL) is __________ (correct to two decimal places).
41.42 %(± 0.15 accepted)
Explanation
For a laminar boundary layer, δ ∝ √x (Blasius solution). Doubling the plate length: δnew/δL = √(2L/L) = √2 ≈ 1.4142, i.e. a (√2−1)×100% ≈ 41.42% increase.
Source: GATE ME 2018 Session 2 (Set 2) (2018)
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