Darcy_Leak

Syntax

Bc Lumped_Disting For Momentum ([{of} SpeciesName] | [{in} MaterialPhaseName] | [{ls} {a | b | c}]) {@ | at | for | on | over} Mesh Extent Name ([Touching TouchingMeshExtent] | [Opposing OpposingMeshExtent]) = Darcy_Leak [Using Data Specification Data Spec Name] ([P_Ref = p_ref] | [L = l] | K = k | [Pressure = pressure])

Summary

Darcy leak model for momentum distinguishing condition

Description

This model implements a vector distinguishing condition that allows fluid to “leak” through a boundary according to a Darcy’s Law like relationship:

\v - \dot{\vector {x}}\bcdot\n\n - \frac{K}{L\viscosity} \left(P - P_{ref}\right) \n = \vector{0}.

Here \n is the outward unit normal to the boundary, \v is the velocity, \dot{\vector { x }} is the time derivative of the mesh boundary position and P is the fluid pressure. K is the permeability of the boundary, \viscosity is the viscosity, P_{ref} is a reference pressure (defaults to zero) and L is a length scale for the pressure drop (defaults to unity).

Note that the second term ensures that the resulting velocity is relative to any boundary motion that arises in moving mesh problems. For problems on fixed meshes this term is automatically excluded.

An alternate pressure field can be used by provided the optional parameter PRESSURE.

Parameter

Value

Default

{of}

{of | species | subindex}

–

SpeciesName

string

–

{in}

{in | material_phase}

–

MaterialPhaseName

string

–

{ls}

{levelset_phase | ls}

–

Mesh Extent Name

string

–

TouchingMeshExtent

string

–

OpposingMeshExtent

string

–

Data Spec Name

string

–

p_ref

real

0

l

real

1

k

real

–

pressure

“string”

–