The GATE Grind

GATE 2026 AE – Question 15

Aerodynamics · Two-dimensional potential flow: sources, sinks, doublets, point vortex and Bernoulli's equation · 1 mark · Multiple choice

In fluid dynamics, d'Alembert's paradox refers to which one of the following?

  1. Deviation of drag from $D \propto v^2$ at very low speeds
  2. Deviation of drag from $D \propto v^2$ at high subsonic speeds
  3. Prediction of zero drag by potential flow theory
  4. Presence of shocks in transonic flows

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Show answer and explanation

Correct answer: (C) Prediction of zero drag by potential flow theory

Explanation

d'Alembert's paradox is that inviscid, irrotational, steady flow past a body gives no drag force, which disagrees with experience.