Description🔗
The semiPermeableBaffleMassFraction
is a boundary condition that provides
a mass-fraction boundary condition for a semi-permeable baffle.
This condition models a baffle which is permeable to a some species and
impermeable to others. It must be used in conjunction with the
corresponding velocity condition,
semiPermeableBaffleVelocity
.
The mass flux of a species is calculated as a coefficient multiplied by the difference in mass fraction across the baffle.
\[\phi_{Yi} = c A (Y_i - Y_{i,n})\]where:
Property | Description |
---|---|
\(\phi_{Yi}\) | Flux of the permeable species [kg/s] |
\(c\) | Transfer coefficient [kg/m^2/s] |
\(A\) | Patch face area [m^2] |
\(Y_i\) | Mass fraction on the patch [-] |
\(Y_{i,n}\) | Mass fraction on the neighbour patch [-] |
A species that the baffle is permeable to will, therefore, have a coefficient greater than zero, whilst a species that does not transfer will have a coefficient equal to zero.
This condition calculates the species flux. The fluxes are summed up by the velocity condition to generate the net mass transfer across the baffle. This mass-fraction condition then generates a corrective diffusive flux to ensure that the correct amounts of the permeable species are transferred.
Usage🔗
The condition requires entries in both the boundary and field files.
Boundary file🔗
<patchName>
{
type patch;
...
}
Field file🔗
<patchName>
{
// Mandatory entries
type semiPermeableBaffleMassFraction;
// Optional entries
c <scalar>;
phi <word>;
// Inherited entries
...
}
where:
Property | Description | Type | Required | Default |
---|---|---|---|---|
type |
Type name: semiPermeableBaffleMassFraction
|
word | yes | - |
c |
Transfer coefficient | scalar | no | 0 |
phi |
Name of flux field | word | no | phi |
The inherited entries are elaborated in:
- mappedPatchBase.H
- mixedFvPatchFields.H
Further information🔗
Tutorial:
- N/A
Source code:
API:
History:
- Introduced in version v2206