Last updated: March 2, 2026 by Maria Gonzalez

Reynolds Number and Flow Regimes

Formula

The Reynolds number (Re) is a dimensionless quantity that predicts flow behavior. Re = ρvD/μ, where ρ is density, v is velocity, D is diameter, and μ is dynamic viscosity. Below 2300 flow is laminar; above 4000 it is turbulent; between is transitional.

Common use cases:

  • Pipe flow classification
  • Aerodynamic analysis
  • Chemical reactor design

Frequently Asked Questions

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Maria Gonzalez

Registered Dietitian, RD, MPH

Maria is a Registered Dietitian with a Master's in Public Health. She focuses on evidence-based nutrition assessment tools including BMI, calorie calculations, and body composition analysis.

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