zeroGradient

Description

The zeroGradient function object creates a volume field with zero-gradient boundary conditions from another volume field.

The result can be used, for example, to post-process near-wall field 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 zeroGradient function object by using functions sub-dictionary in system/controlDict file:

zeroGradient1
{
    // Mandatory entries (unmodifiable)
    type            zeroGradient;
    libs            (fieldFunctionObjects);

    // Mandatory entries (runtime modifiable)
    fields          (<field1> ... <fieldN>); \\(U "(T|k|epsilon|omega)");

    // Optional entries (runtime modifiable)
    result          @@<name>;

    // 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: zeroGradient	word	yes	-
libs	Library name: fieldFunctionObjects	word	yes	-
fields	Name of the operand fields	wordList	yes	-
result	Name of the output field	word	no	zeroGradient(@@)

The inherited entries are elaborated in:

• functionObject

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 would not benefit e.g. processor, empty, zeroGradient, symmetry patches. This check should also prevent processing fields multiple times.

Further information

Tutorial:

• cavity

Source code:

• zeroGradient

API:

• Foam::functionObjects::zeroGradient

History: Introduced in version v1612+