GfsSourceViscosity

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Revision as of 21:58, 21 April 2009
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(The viscosity is the dynamic viscosity not kinematic)
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Revision as of 11:32, 20 October 2012
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(Added comment on dynamic viscosity)
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To sum up, using GfsSourceViscosity is safe in all cases, regardless of whether the viscosity is uniform. To sum up, using GfsSourceViscosity is safe in all cases, regardless of whether the viscosity is uniform.
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 +In the case where the density (specified using [[GfsPhysicalParams]]) is not unity, the diffusion coefficient is the [[w:Viscosity#Viscosity_coefficients|dynamic viscosity coefficient]].
The syntax in parameter files is: The syntax in parameter files is:

Revision as of 11:32, 20 October 2012

GfsSourceViscosity solves the diffusion equation for the velocity (a vector quantity obviously) while GfsSourceDiffusion solves the diffusion equation for a scalar quantity. In the case of a spatially uniform viscosity the two are strictly equivalent since — in the case of an incompressible fluid — the vector diffusion equation for the velocity can be split in independent scalar diffusion equations for each of the Cartesian components of the velocities.

To sum up, using GfsSourceViscosity is safe in all cases, regardless of whether the viscosity is uniform.

In the case where the density (specified using GfsPhysicalParams) is not unity, the diffusion coefficient is the dynamic viscosity coefficient.

The syntax in parameter files is:

[ GfsSourceVelocity ] [ GfsDiffusion ]

where GfsDiffusion defines the dynamic viscosity of the fluid.

Examples

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