Viscosity models

Viscosity models#

This section describes the current models of molecular viscosity implemented in FELiCS.

Sutherland model for molecular viscosity#

The Sutherland model describes how molecular viscosity changes with temperature for a specific gas.

Assumptions:

  • ideal gas behavior

  • negligible intermolecular forces except during collisions

  • molecular viscosity is only a function of the gas composition and the temperature

Example use case:

References:

Nomenclature:

  • \(T\): temperature

  • \(T_0\): reference temperature

  • \(\mu\): molecular dynamic viscosity at temperature \(T\)

  • \(\mu_0\): reference dynamic viscosity at reference temperature \(T_0\)

  • \(C\): Sutherland’s constant

The Sutherland model is

\[ \mu = \mu_0 \frac{T_0 +C}{T+C}(\frac{T}{T_0})^{3/2} \]
It is used for calculating the dynamic molecular viscosity of the mean flow.

Note

The linearized form of the Sutherland model is not implemented in FELiCS yet.

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