Descriptionπ
The LambVector
function object computes
βLamb vectorβ [m/s2] [79] (p. 77) which is the
cross product of a velocity vector [m/s] and vorticity vector [1/s].
LambVector
is defined as follows:
where \(\vec{\omega}(\mathbf{x},t) \equiv \vec{\omega}\) is the vorticity vector, and \(\u (\mathbf{x}, t) \equiv \u\) the velocity vector.
The motivation of LambVector
function object is the literature-reported
quantitative connection between the Lamb vector (divergence) and the spatially
localised instantaneous fluid motions, e.g. high- and low-momentum fluid
parcels, which possess considerable level of capacity to affect the rate of
change of momentum, and to generate forces such as drag.
Operandsπ
Operand | Type | Location |
---|---|---|
input | volVectorField |
$FOAM_CASE/<time>/<inpField> |
output file | - | - |
output field | volScalarField |
$FOAM_CASE/<time>/<outField> |
Usageπ
Example of the LambVector
function object
by using functions
sub-dictionary in system/controlDict
file:
LambVector1
{
// Mandatory entries (unmodifiable)
type LambVector;
libs (fieldFunctionObjects);
// Optional (inherited) entries
field <inpField>;
result <fieldResult>;
region region0;
enabled true;
log true;
timeStart 0;
timeEnd 1000;
executeControl timeStep;
executeInterval 1;
writeControl timeStep;
writeInterval 1;
}
where the entries mean:
Property | Description | Type | Required | Default |
---|---|---|---|---|
type | Type name: LambVector | word | yes | - |
libs | Library name: fieldFunctionObjects | word | yes | - |
The inherited entries are elaborated in:
Usage by the postProcess
utility is not available.
An example of the usage involving the divergence computation of the LambVector
can be seen below:
In controlDict.functions
:
LambVector1
{
type LambVector;
libs (fieldFunctionObjects);
field U;
}
div1
{
type div;
libs (fieldFunctionObjects);
field LambVector;
}
fieldAverage1
{
type fieldAverage;
libs (fieldFunctionObjects);
writeControl writeTime;
fields
(
LambVector
{
mean on;
prime2Mean off;
base time;
}
div(LambVector)
{
mean on;
prime2Mean off;
base time;
}
);
}
Please note that if default divScheme
is none
, in fvSchemes.divSchemes
, a
numerical scheme should be chosen for related quantities, e.g. div(LambVector)
as follows:
div(LambVector) Gauss linear;
Further informationπ
Tutorial:
-
pisoFoam
cavity
tutorial: $FOAM_TUTORIALS/incompressible/pisoFoam/RAS/cavity
Source code:
API:
Related:
History: