reynolds number: meaning, definition, pronunciation and examples
LowTechnical/Scientific
Quick answer
What does “reynolds number” mean?
A dimensionless number used in fluid mechanics to predict flow patterns in different fluid flow situations.
Audio
Pronunciation
Definition
Meaning and Definition
A dimensionless number used in fluid mechanics to predict flow patterns in different fluid flow situations.
In engineering and physics, a parameter that quantifies the ratio of inertial forces to viscous forces for a fluid flow, indicating whether the flow is laminar (smooth) or turbulent.
Dialectal Variation
British vs American Usage
Differences
No significant differences in meaning or usage. British English typically uses 'Reynolds number', while American English may also use 'Reynolds-number' or 'Re' in informal technical writing.
Connotations
Highly specific scientific/engineering term with no cultural connotations.
Frequency
Rare outside of engineering, physics, and related technical fields.
Grammar
How to Use “reynolds number” in a Sentence
The Reynolds number is + adjective (high/critical).At a Reynolds number of + [value].Calculate/find/determine the Reynolds number for + [object/flow].Vocabulary
Collocations
Examples
Examples of “reynolds number” in a Sentence
adjective
British English
- Reynolds-number-dependent effects were analysed.
- The model is only valid for low-Reynolds-number flows.
American English
- Reynolds-number-dependent effects were analyzed.
- The simulation uses a high-Reynolds-number turbulence model.
Usage
Meaning in Context
Business
Not used.
Academic
Used in engineering, physics, and applied mathematics lectures, papers, and textbooks.
Everyday
Virtually never used.
Technical
Core term in fluid dynamics, aerodynamics, chemical engineering, and HVAC design.
Vocabulary
Synonyms of “reynolds number”
Neutral
Weak
Watch out
Common Mistakes When Using “reynolds number”
- Misspelling as 'Reynold's number' (incorrect apostrophe).
- Using it as a plural (e.g., 'Reynolds numbers are' – acceptable in some contexts but the singular 'the Reynolds number' is more common for the concept).
- Confusing it with other dimensionless numbers like the Mach number.
FAQ
Frequently Asked Questions
Osborne Reynolds, a 19th-century British engineer and physicist.
No, it is a specialised term confined to scientific and engineering contexts.
There is no fixed value, but flows above approximately 4000 in a pipe are generally considered turbulent (high Re).
Yes, it applies to any Newtonian fluid, including air, water, and oil.
A dimensionless number used in fluid mechanics to predict flow patterns in different fluid flow situations.
Reynolds number is usually technical/scientific in register.
Reynolds number: in British English it is pronounced /ˈrɛnəldz ˈnʌmbə/, and in American English it is pronounced /ˈrɛnəldz ˈnʌmbər/. Tap the audio buttons above to hear it.
Learning
Memory Aids
Mnemonic
Remember Osborne REYNOLDS studied fluid flow. His NUMBER tells you if the flow is a gentle REINdeer (laminar) or a wild REINstorm (turbulent).
Conceptual Metaphor
FLUID FLOW IS A JOURNEY (laminar is a smooth motorway; turbulent is a rough, winding path. The Reynolds number is the map legend telling you which path you're on).
Practice
Quiz
What does the Reynolds number primarily compare?