Description🔗
The ddt2
function object computes the magnitude or magnitude squared of
the Eulerian time derivative of an input volume field for time-variant
simulations (not appropriate to steady-state simulations).
The result can be further used for determining e.g. variance or RMS values.
Operands🔗
Operand | Type | Location |
---|---|---|
input | vol<Type>Field |
$FOAM_CASE/<time>/<inpField> |
output file | - | - |
output field | vol<Type>Field |
$FOAM_CASE/<time>/<outField> |
where <Type>=Scalar/Vector/SphericalTensor/SymmTensor/Tensor
.
Usage🔗
Example of the ddt2
function object
by using functions
sub-dictionary in system/controlDict
file:
ddt21
{
// Mandatory entries (unmodifiable)
type ddt2;
libs (fieldFunctionObjects);
// Mandatory entries (runtime modifiable)
fields (<field1> <field2> ... <fieldN>);
// Optional entries (unmodifiable)
mag false;
// Optional entries (runtime modifiable)
result d@@dt2;
// Optional (inherited) entries
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: ddt2 | word | yes | - |
libs | Library name: fieldFunctionObjects | word | yes | - |
fields | Names of the operand fields | wordList | yes | - |
mag | Compute ‘mag’ instead of ‘magSqr’ | bool | no | false |
result | Name of results | word | no | magSqr(ddt2(@@)) |
The inherited entries are elaborated in:
Usage by the postProcess
utility is not available.
Notes on entries🔗
A list of fields can contain exact names or regular expressions.
The token \@\@
in the result name is replaced by the name of the source
field. In the special case of a single source field (specified as
a non-regex), the \@\@
token checking is suppressed.
The function object will skip over fields that appear to have already been processed (ie, their names are similar to the output names).
Further information🔗
Tutorial:
Source code:
API:
History:
- Introduced in version v1612+