The LambVector
function object computes 'Lamb vector' [m/s2] [84] (p. 77) which is the cross product of a velocity vector [m/s] and vorticity vector [1/s].
LambVector
is defined as follows:
\[ \mathbf{l} = \vec{\omega} \times \u \]
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.
Operand | Type | Location |
---|---|---|
input | volVectorField | $FOAM_CASE/<time>/<inpField> |
output file | - | - |
output field | volScalarField | $FOAM_CASE/<time>/<outField> |
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;
Tutorial:
channel395DFSEM
tutorial: $FOAM_TUTORIALS/incompressible/pimpleFoam/LES/channel395DFSEMSource code:
Related:
History