Project ForgeFluid Mechanics
Bernoulli's Equation & Flow
GATE 2007
Medium
Consider an incompressible laminar boundary layer flow over a flat plate of length L, aligned with the direction of an oncoming uniform free stream. If F is the ratio of the drag force on the front half of the plate to the drag force on the rear half, then
- AF < 1/2
- BF = 1/2
- CF = 1
- F > 1
Explanation
For a laminar boundary layer, cumulative drag from 0 to x scales as √x. Front-half drag ∝ √(L/2); rear-half drag ∝ √L−√(L/2) = √L(1−1/√2). Ratio F=√(L/2)/[√L(1−1/√2)] = (1/√2)/(1−1/√2) ≈ 2.41 > 1 (the boundary layer is thinner and shear stress higher near the leading edge).
Source: GATE ME 2007 (2007)
This question is part of a 15-day revision cycle — sign in and Project Forge will bring it back the day before you'd forget it.