Part 11: Characteristic Numbers·115 entries

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11-5.3

Rayleigh number

URNurn:iso:std:iso:80000:-11:ed-2:en:item:11-5.3

https://metanorma.github.io/isq-smart/quantities/part-11/t11-5.3
urn:iso:std:iso:80000:-11:ed-2:en:item:11-5.3

ISQ Identifiers

ISO

urn:iso:std:iso:80000:-11:ed-2:en:item:11-5.3

IEC

urn:iec:std:iec:80000-11:2019:::item:11-5.3

Designations

ENRayleigh number

FRnombre de Rayleigh

Symbol

R a

Notation systems

Rendered

R a

AsciiMath

Ra

LaTeX

R a

Definition

relation between buoyancy forces due to thermal expansion and viscous forces in free convection in buoyancy driven flow near a heated surface perpendicular to the gravity force, expressed by

$R a = \frac{l^{3} g α_{V} Δ T}{v α}$ ; where

$l$ :: is distance (ISO 80000-3: Space and time) from the wall,

$g$ :: is acceleration of free fall (ISO 80000-3: Space and time),

$α_{V}$ :: is cubic expansion coefficient (ISO 80000-5: Thermodynamics) of the fluid,

$Δ T$ :: is difference of thermodynamic temperature (ISO 80000-5: Thermodynamics) between surface of the wall and the fluid far away from the wall,

$v$ :: is kinematic viscosity (ISO 80000-4: Mechanics) of the fluid, and

$α$ :: is thermal diffusivity (ISO 80000-5: Thermodynamics) of the fluid

relation entre la poussée d'Archimède due à la dilatation thermique et les forces visqueuses dans le contexte d'une convection libre dans un écoulement induit par la poussée hydrostatique à proximité d'une surface chauffée perpendiculaire à la force de pesanteur, exprimée par:

$R a = \frac{l^{3} g α_{V} Δ T}{v α}$ ; où

$l$ :: est la distance (ISO 80000-3: Space and time) par rapport à la paroi;

$g$ :: est l'accélération due à la pesanteur (ISO 80000-3: Space and time);

$α_{V}$ :: est le coefficient de dilatation volumique (ISO 80000-5: Thermodynamics) du fluide;

$Δ T$ :: est la différence de température thermodynamique (ISO 80000-5: Thermodynamics) entre la surface de la paroi et le fluide à distance de la paroi;

$v$ :: est la viscosité cinématique (ISO 80000-4: Mechanics) du fluide; et

$α$ :: est la diffusivité thermique (ISO 80000-5: Thermodynamics) du fluide

Notes

The Rayleigh number is also given by

$R a = G r \cdot P r$ ; where

$G r$ :: is the Grashof number (Grashof number), and

$P r$ :: is the Prandtl number (Prandtl number).

Le nombre de Rayleigh est également donné par:

$R a = G r \cdot P r$ ; où

$G r$ :: est le nombre de Grashof (Grashof number); et

$P r$ :: est le nombre de Prandtl (Prandtl number).

Referenced by

Grashof number

Concept HierarchyPendrill (2024)

1dimensionless quantitiesLevel 0 · Kind

Broader concepts

◇ dimensionless quantities

Ontology
isq:Quantity smart:TermEntry

Class Hierarchy

smart:Entity smart:TermEntryisq:Quantity

A physical quantity as defined in ISO/IEC 80000, with associated symbols, definitions, and units of measurement.

Instance IRI

isq:t11-5.3

Properties

isq:QuantityShape

Property	Value
rdf:type	isq:Quantity smart:TermEntry
dcterms:identifier	11-5.3
skosxl:prefLabel	"Rayleigh number"@en
skosxl:altLabel	"Ra"@en
skos:definition	relation between buoyancy forces due to thermal expansion and viscous forces in free convection in buoyancy driven flow …
skos:note	The Rayleigh number is also given by stem:[Ra = Gr * Pr]; where stem:[Gr]:: is the Grashof number (<<t11-4.4>>), and s…
isq:hasDimension	isq:Dimension
smart:hasBindingnessType	bindingness-type:normative
dcterms:isPartOf	isq:part-11

Related Entities

isq:QuantityShape isq:part-11 isq:Unit isq:Dimension isq:hasDimension smart:TermEntry