Name | Formula | Ratio | Details |
Bi
Biot |
h L k |
Surface Conductance Internal Conductance of Solid |
h | - | heat xfer coef at surface |
L | - | characteristic length of conduction. Ex: radius. |
k | - | thermal conductivity of solid |
|
Gr
Grashof |
g β L3 Δ T
ν 2 |
Bouyancy Force Viscous Force |
g | - | acceleration of gravity |
β | - | coef of thermal expansion of fluid |
L | - | characteristic length of object |
Δ T | - | wall temp - ambient temp |
ν | - | kinematic viscosity |
|
Nu
Nusselt |
h L k |
Convection at Surface Conduction at Surface |
h | - | heat xfer coef at surface |
L | - | characteristic length of object |
k | - | thermal conductivity of fluid |
|
Pr
Prandtl |
μ cp k |
Diffusion of Momentum Diffusion of Heat |
μ | - | viscosity of fluid |
cp | - | specific heat of fluid |
k | - | thermal conductivity of fluid |
|
Re
Reynolds |
ρ V L μ |
Intertial Force Viscous Force |
ρ | - | density of fluid |
V | - | far field fluid velocity |
L | - | characteristic length of object |
μ | - | viscosity of fluid |
|
St
Stanton |
h ρ V cp |
Heat Xfer at Wall Energy Xported by Stream |
h | - | heat xfer coefficient |
ρ | - | density of fluid |
V | - | far field fluid velocity |
cp | - | specific heat of fluid |
|