11-4.1

Reynolds number

Re

inertial forces / viscous forces

11-4.2

Euler number

Eu

pressure drop / kinetic energy per volume

11-4.3

Froude number

Fr

inertial forces / gravitational forces

11-4.4

Grashof number

Gr

thermal buoyancy forces / viscous forces

11-4.5

Weber number

We

inertial forces / surface-tension forces

11-4.6

Mach number

Ma

speed of flow / speed of sound

11-4.7

Knudsen number

Kn

mean free path / characteristic length

11-4.8

Strouhal number

Sr

characteristic frequency / characteristic speed

11-4.9

drag coefficient

c_D

drag force / inertial force

11-4.10

Bagnold number

Bg

drag and gravitational force / inertial force

11-4.11

Bagnold number

Ba₂

drag force / viscous force, solid particles

11-4.12

lift coefficient

c_l

lift force / inertial force

11-4.13

thrust coefficient

c_t

thrust force / inertial force

11-4.14

Dean number

Dn

centrifugal force / inertial force, curved pipe

11-4.15

Bejan number

Be

mechanical work / frictional energy loss

11-4.16

Lagrange number

Lg

mechanical work / frictional energy loss, Lagrange form

11-4.17

Bingham number

Bm

yield stress / viscous stress

11-4.18

Hedström number

He

yield stress / viscous stress, at flow limit

11-4.19

Bodenstein number

Bd

convective / diffusive matter transfer

11-4.20

Rossby number

Ro

inertial forces / Coriolis forces

11-4.21

Ekman number

Ek

viscous forces / Coriolis forces

11-4.22

elasticity number

El

relaxation time / diffusion time

11-4.23

Darcy friction factor

f_D

pressure loss / pipe-wall friction

11-4.24

Fanning number

f_F

wall shear stress / dynamic pressure

11-4.25

Goertler number

Go

centrifugal effects / viscous effects, boundary layer

11-4.26

Hagen number

Hg

pressure-gradient force / viscous force

11-4.27

Laval number

La

flow speed / critical sound speed, nozzle throat

11-4.28

Poiseuille number

Poi

pressure force / viscous force, pipe flow

11-4.29

power number

Ne

agitator power / inertial power

11-4.30

Richardson number

Ri

potential energy / kinetic energy

11-4.31

Reech number

Re_e

object speed / wave speed, submerged

11-4.32

Stokes number

Stk

friction force / inertial force, particles in flow

11-4.33

Stokes number

Stk₁

friction force / inertial force, vibrating particles

11-4.34

Stokes number

Stk₂

drag / inertia, rotameter calibration

11-4.35

Stokes number

Stk₃

viscous force / gravity force, settling particles

11-4.36

Stokes number

Stk₄

drag force / internal friction force, particles

11-4.37

Laplace number

La

capillary force / viscous force, free surface

11-4.38

Blake number

Bl

inertial force / viscous force, porous medium

11-4.39

Sommerfeld number

So

viscous force / load force, lubrication

11-4.40

Taylor number

Ta

centrifugal force / viscous force, rotating flow

11-4.41

Galilei number

Ga

gravitational force / viscous force, fluid film

11-4.42

Womersley number

Wo

inertial forces / viscous forces, oscillating flow

11-5.1

Fourier number

Fo

heat conduction rate / thermal storage rate

11-5.2

Péclet number

Pe

convective / conductive heat transfer rate

11-5.3

Rayleigh number

Ra

thermal buoyancy forces / viscous forces, free convection

11-5.4

Froude number

Fr*

gravitational forces / thermodiffusion forces

11-5.5

Nusselt number

Nu

convective / conductive heat transfer at a surface

11-5.6

Biot number

Bi

internal / surface thermal resistance

11-5.7

Stanton number

St

wall heat transfer / fluid heat-capacity flow

11-5.8

j-factor

j

heat transfer / mass transfer, Colburn analogy

11-5.9

Bejan number

Be₁

mechanical work / frictional and thermal-diffusion losses

11-5.10

Bejan number

Be_S

heat-transfer efficiency / entropy generation

11-5.11

Stefan number

Ste

sensible heat / latent heat, phase change

11-5.12

Brinkman number

Br

viscous heat production / wall heat conduction

11-5.13

Clausius number

Cl

kinetic energy transfer / thermal conduction

11-5.14

Carnot number

Ca

maximum thermodynamic (Carnot) efficiency

11-5.15

Eckert number

Ec

kinetic energy / enthalpy difference

11-5.16

Graetz number

Gz

convective / conductive heat, laminar pipe

11-5.17

heat transfer number

K_Q

heat flow / kinetic energy of flow

11-5.18

Pomerantsev number

Po

generated heat / conducted heat in a body

11-5.19

Boltzmann number

Bz

convective heat / radiant heat

11-5.20

Stark number

Sk

radiant heat / conductive heat

11-6.1

Fourier number

Fo*

diffusive mass transfer / storage rate

11-6.2

Péclet number

Pe*

advective / diffusive mass transfer rate

11-6.3

Grashof number

Gr*

buoyancy forces / viscous forces, natural convection

11-6.4

Nusselt number

Nu*

mass flux / molecular-diffusion flux

11-6.5

Stanton number

St*

perpendicular / parallel surface mass transfer

11-6.6

Graetz number

Gz*

advective / radial diffusive mass transfer

11-6.7

mass transfer factor

j*

interface mass transfer / parallel flux, Chilton-Colburn

11-6.8

Atwood number

At

density difference / density sum, two fluids

11-6.9

Biot number

Bi*

interface / interior mass transfer rate

11-6.10

Morton number

Mo

gravitational forces / viscous forces, bubbles

11-6.11

Bond number

Bo

gravitational and inertial force / capillary force

11-6.12

Archimedes number

Ar

buoyancy forces / viscous forces, density difference

11-6.13

expansion number

Ex

buoyancy force / inertial force, rising bubbles

11-6.14

Marangoni number

Mg

surface-tension convection / thermal diffusion

11-6.15

Lockhart-Martinelli parameter

Lp

two-phase mass-flow-rate ratio by density

11-6.16

Bejan number

Be*

mechanical work / frictional and diffusion losses

11-6.17

cavitation number

Ca

static-vapour head / dynamic head

11-6.18

absorption number

Ab

mass flow rate / surface area, gas absorption

11-6.19

capillary number

Ca

gravitational forces / capillary forces

11-6.20

dynamic capillary number

Ca*

viscous force / capillary force, interface

11-7.1

Prandtl number

Pr

kinematic viscosity / thermal diffusivity

11-7.2

Schmidt number

Sc

kinematic viscosity / diffusion coefficient

11-7.3

Lewis number

Le

thermal diffusivity / diffusion coefficient

11-7.4

Ohnesorge number

Oh

viscous force / root of inertia times capillary force

11-7.5

Cauchy number

Cy

inertia forces / compression forces

11-7.6

Hooke number

Ho₂

inertia forces / linear-stress forces

11-7.7

Weissenberg number

Wi

shear rate times relaxation time

11-7.8

Deborah number

De

relaxation time / observation time

11-7.9

Lorentz number

Lo

electrical conductivity / thermal conductivity

11-7.10

compressibility number

Z

real-gas / ideal-gas compressibility factor

11-8.1

Reynolds magnetic number

Rm

inertial force / magneto-dynamic viscous force

11-8.2

Batchelor number

Bt

inertia / magneto-dynamic diffusion

11-8.3

Nusselt electric number

Ne_e

convective / diffusive ion current

11-8.4

Alfvén number

Al

flow speed / Alfvén wave speed

11-8.5

Hartmann number

Ha

magnetically induced stress / viscous force

11-8.6

Cowling number

Co

magnetic / kinematic energy density

11-8.7

Stuart electrical number

Se

electric / kinematic energy density

11-8.8

magnetic pressure number

N_mp

gas pressure / magnetic pressure

11-8.9

Chandrasekhar number

Q

Lorentz force / viscous force

11-8.10

Prandtl magnetic number

Pr_m

kinematic viscosity / magnetic viscosity

11-8.11

Roberts number

Ro_m

thermal diffusivity / magnetic viscosity

11-8.12

Stuart number

N_St

magnetic force / inertial force

11-8.13

magnetic number

N_mg

magnetic body force / viscous force

11-8.14

electric field parameter

E_f

Coulomb force / Lorentz force

11-8.15

Hall number

Hl

gyrofrequency / collision frequency

11-8.16

Lundquist number

Lu

Alfvén speed / magneto-dynamic diffusion speed

11-8.17

Joule magnetic number

Jo_m

Joule heating / magnetic field energy

11-8.18

Grashof magnetic number

Gr_m

thermo-magnetic buoyancy / viscous force

11-8.19

Naze number

Na

Alfvén wave speed / sound speed

11-8.20

Reynolds electric number

Re_e

fluid speed / charged-particle drift speed

11-8.21

Ampère number

Am

electric surface current / magnetic field

11-9.1

Arrhenius number

α

chemical activation energy / thermal energy

11-9.2

Landau-Ginzburg number

κ

penetration depth / coherence length