Project ForgeFluid Mechanics
Bernoulli's Equation & Flow
GATE 2015
Hard
Air (ρ=1.2 kg/m³ and kinematic viscosity, ν=2×10⁻⁵ m²/s) with a velocity of 2 m/s flows over the top surface of a flat plate of length 2.5 m. If the average value of friction coefficient is Cf=1.328/√Rex, the total drag force (in N) per unit width of the plate is __________.
0.016 N(± 0.0003 accepted)
Explanation
Re_L = VL/ν = 2×2.5/(2×10⁻⁵) = 250,000. Cf = 1.328/√250000 ≈ 0.002656. Drag per unit width F = Cf×0.5×ρ×V²×L = 0.002656×0.5×1.2×4×2.5 ≈ 0.0159 N.
Source: GATE ME 2015 (Session 1) (2015)
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