zeroGradient

Table of Contents

• Description
  • Operands
• Usage
  • Notes on entries
• Further information

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

• ie, only processor, empty, zeroGradient, symmetry patches. This check should also prevent processing fields multiple times.

Further information

Tutorial:

• $FOAM_TUTORIALS/incompressible/pisoFoam/RAS/cavity

Source code:

• Foam::functionObjects::zeroGradient

History

• Introduced in version v1612+