Scope
Names, symbols, and definitions for characteristic numbers (dimensionless quantities) used in the description of transport and transfer phenomena — Reynolds, Mach, Prandtl, Nusselt, and many more.
What You'll Find
Characteristic numbers are quantities of dimension one that describe behavior of natural and technical processes or reveal similarities between different processes
Often expressed as ratios of forces, energy, or characteristic times
The same equation can define different numbers when applied to different physical processes
Organized by process type: dynamic similarity, heat and mass transfer, magnetohydrodynamics, radiation transfer, and turbulence
Includes only the most commonly used numbers — alternative forms (inversions, squared versions) are generally deprecated
Obtain the Standard
Published by the International Organization for Standardization (ISO). Edition 2019. Developed by ISO/TC 12 — Quantities and units.
Browse Entries
115 quantities defined in Part 11