Description🔗
The activePressureForceBaffleVelocity
is a velocity boundary condition that
simulates the opening or closure of a baffle due to area averaged pressure or
force delta, between both sides of the baffle. This is achieved by merging the
behaviours of wall
and cyclic
baffles.
The baffle joins two mesh regions, where the open fraction determines the interpolation weights applied to each cyclic- and neighbour-patch contribution. This condition is meant to be used in an extra wall beyond an existing cyclic patch pair.
The baffle is activated when the area weighted pressure difference between
master and slave patches is larger then minThresholdValue
.
Once the threshold is crossed, the baffle is activated and continues to open or close at a fixed rate using
\[x = x_{old} + s \, \frac{\Delta t}{T}\]where:
Property | Description |
---|---|
\(x\) | Baffle open fraction [0-1] |
\(x_{old}\) | Baffle open fraction on previous evaluation [0-1] |
\(\Delta t\) | Simulation time step [s] |
\(T\) | Time taken to open the baffle [s] |
\(s\) | Sign for orientation: 1 to open or -1 to close |
The open fraction is then applied to scale the patch areas.
Usage🔗
The condition requires entries in both the boundary and field files.
Boundary file🔗
<patchName>
{
type wall;
...
}
Field file🔗
<patchName>
{
// Mandatory entries
type activePressureForceBaffleVelocity;
cyclicPatch <word>;
orientation <label>;
openFraction <scalar>;
openingTime <scalar>;
maxOpenFractionDelta <scalar>;
minThresholdValue <scalar>;
forceBased <bool>;
opening <bool>;
// Optional entries
p <word>;
// Inherited entries
...
}
where:
Property | Description | Type | Required | Default |
---|---|---|---|---|
type |
Type name: activeBaffleVelocity
|
word | yes | - |
cyclicPatch |
Name of cyclic patch | word | yes | - |
orientation |
Flag to switch flow direction, either 1 or -1 | label | yes | - |
openFraction |
Current open fraction of patch [0-1] | scalar | yes | - |
openingTime |
Time taken to open the baffle | scalar | yes | - |
maxOpenFractionDelta |
Max open fraction change per timestep | scalar | yes | - |
minThresholdValue |
Min absolute pressure or force difference for activation | scalar | yes | - |
forceBased |
Force (true) or pressure-based (false) activation | bool | yes | - |
opening |
Baffle is opening (true) or closing (false) | bool | yes | - |
p |
Name of pressure field | word | no | p |
The inherited entries are elaborated in:
- fixedValueFvPatchField.H
Further information🔗
Tutorial:
Source code:
API:
History:
- Introduced in version 2.0.0