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Alfvén Number

The Alfvén number describes the relative scale for phenomena within an Alfvén wave, a type of magnetohydrodynamic wave in which ions oscillate in response to a restoring force provided by an effective tension on the magnetic field lines.

The Alfve'n number increases with the characteristic speed of the system. Quadratic increases in magnetic permeability and density also increase the Alfve'n number. The number descreases with increasing magnetic flux density.

Formula

QuantityVariable["Al", "AlfvenNumber"] == (QuantityVariable["v", "Speed"]*Sqrt[QuantityVariable["μ", "MagneticPermeability"]*QuantityVariable["ρ", "MassDensity"]])/QuantityVariable["B", "MagneticFluxDensity"]

symbol description physical quantity
Al Alfvén number "AlfvenNumber"
B magnetic flux density "MagneticFluxDensity"
v characteristic speed "Speed"
μ magnetic permeability "MagneticPermeability"
ρ mass density "MassDensity"

Forms

Examples

Get the resource:

In[1]:=
ResourceObject["Alfvén Number"]
Out[1]=

Get the formula:

In[2]:=
FormulaData[ResourceObject["Alfvén Number"]]
Out[2]=

Use some values:

In[3]:=
FormulaData[ ResourceObject[ "Alfvén Number"], {QuantityVariable["B","MagneticFluxDensity"] -> Quantity[1, "Milliteslas"], QuantityVariable["Al","AlfvenNumber"] -> 1, QuantityVariable["v","Speed"] -> Quantity[1, ("Meters")/("Seconds")]}]
Out[3]=

Source Metadata

  • Creator:
  • Date: 1942

Publisher Information