The GATE Grind

GATE 2026 MT – Question 43

Transport Phenomena and Rate Processes · Fluid flow and momentum transfer · 2 marks · Multiple select

Choose the correct option(s). Permeability of a porous bed made of spherical particles is/are:

  1. Independent of particle size
  2. Increases with increase in particle size
  3. Decreases with increase in particle size
  4. Affected by particle size distribution

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Show answer and explanation

Correct answer: (B) Increases with increase in particle size; (D) Affected by particle size distribution

Explanation

For similar porosity and packing, permeability scales approximately as particle diameter squared; larger particles create wider flow passages. Particle-size distribution also matters because fines can occupy voids and change porosity and tortuosity. Therefore **B,D** are true; permeability is neither size-independent nor generally decreasing with increasing particle size.