Sommerfeld Number Formula

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The Sommerfeld number is a dimensionless number that is used in designing a hydrodynamic bearing. Check FAQs
S=((RshaftcR)2)μNP
S - Sommerfeld Number?Rshaft - Radius of Shaft?cR - Radial Clearance?μ - Absolute Viscosity?N - Speed of Rotating Shaft?P - Load per Unit of Area?

Sommerfeld Number Example

With values
With units
Only example

Here is how the Sommerfeld Number equation looks like with Values.

Here is how the Sommerfeld Number equation looks like with Units.

Here is how the Sommerfeld Number equation looks like.

0.0386Edit=((1.35Edit0.09Edit)2)0.001Edit17Edit99Edit
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Sommerfeld Number Solution

Follow our step by step solution on how to calculate Sommerfeld Number?

FIRST Step Consider the formula
S=((RshaftcR)2)μNP
Next Step Substitute values of Variables
S=((1.35m0.09m)2)0.001Pa*s17rev/s99Pa
Next Step Convert Units
S=((1.35m0.09m)2)0.001Pa*s17Hz99Pa
Next Step Prepare to Evaluate
S=((1.350.09)2)0.0011799
Next Step Evaluate
S=0.0386363636363636
LAST Step Rounding Answer
S=0.0386

Sommerfeld Number Formula Elements

Variables
Sommerfeld Number
The Sommerfeld number is a dimensionless number that is used in designing a hydrodynamic bearing.
Symbol: S
Measurement: NAUnit: Unitless
Note: Value should be greater than 0.
Radius of Shaft
Radius of shaft is the distance between the center and the circumference of the shaft.
Symbol: Rshaft
Measurement: LengthUnit: m
Note: Value can be positive or negative.
Radial Clearance
Radial Clearance is a measured value of the total movement of one ring relative to the other in a plane perpendicular to the bearing axis.
Symbol: cR
Measurement: LengthUnit: m
Note: Value should be greater than 0.
Absolute Viscosity
Absolute Viscosity is the measurement of the fluid's internal resistance to flow.
Symbol: μ
Measurement: Dynamic ViscosityUnit: Pa*s
Note: Value can be positive or negative.
Speed of Rotating Shaft
Speed of Rotating Shaft is defined at which a rotating shaft will tend to vibrate violently in the transverse direction if the shaft rotates in the horizontal direction.
Symbol: N
Measurement: FrequencyUnit: rev/s
Note: Value should be greater than 0.
Load per Unit of Area
Load per Unit of Area is the ratio of internal resistive force to the deformation per unit area and can be defined as Stress.
Symbol: P
Measurement: PressureUnit: Pa
Note: Value should be greater than 0.

Other formulas in Dimensionless Numbers category

​Go Reynolds Number
Re=ρ1vfddpμv
​Go Euler Number using Fluid Velocity
Eu=vfluiddPρFluid
​Go Archimedes Number
Ar=[g]Lc3ρFluid(ρB-ρFluid)(μviscosity)2
​Go Weber Number
We=(ρ(V2)Lσ)

How to Evaluate Sommerfeld Number?

Sommerfeld Number evaluator uses Sommerfeld Number = ((Radius of Shaft/Radial Clearance)^(2))*(Absolute Viscosity*Speed of Rotating Shaft)/(Load per Unit of Area) to evaluate the Sommerfeld Number, Sommerfeld number (S) is a dimensionless quantity used extensively in hydrodynamic lubrication analysis. Sommerfeld Number is denoted by S symbol.

How to evaluate Sommerfeld Number using this online evaluator? To use this online evaluator for Sommerfeld Number, enter Radius of Shaft (Rshaft), Radial Clearance (cR), Absolute Viscosity (μ), Speed of Rotating Shaft (N) & Load per Unit of Area (P) and hit the calculate button.

FAQs on Sommerfeld Number

What is the formula to find Sommerfeld Number?
The formula of Sommerfeld Number is expressed as Sommerfeld Number = ((Radius of Shaft/Radial Clearance)^(2))*(Absolute Viscosity*Speed of Rotating Shaft)/(Load per Unit of Area). Here is an example- 0.038636 = ((1.35/0.09)^(2))*(0.001*17)/(99).
How to calculate Sommerfeld Number?
With Radius of Shaft (Rshaft), Radial Clearance (cR), Absolute Viscosity (μ), Speed of Rotating Shaft (N) & Load per Unit of Area (P) we can find Sommerfeld Number using the formula - Sommerfeld Number = ((Radius of Shaft/Radial Clearance)^(2))*(Absolute Viscosity*Speed of Rotating Shaft)/(Load per Unit of Area).
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