reference

Table of Contents

Description

The reference function object computes a field whose values are offset to a reference value obtained by sampling the field at a user-specified location.

The field values are calculated using:

\[ \text{ref}_c = s(f_{c}(t) - f_p + f_{off}) \]

where

\( \text{ref}_c \) = Field values at cell
\( s \) = Optional scale factor (default = 1)
\( f_{c}(t) \) = Current field values at cell at this time
\( f_p \) = Field value at position
\( f_{off} \) = Offset field value (default = 0)

Operands

Operand Type Location
input {vol,surface}<Type>Field $FOAM_CASE/<time>/<inpField>
output file - -
output field {vol,surface}<Type>Field $FOAM_CASE/<time>/<outField>

where <Type>=Scalar/Vector/SphericalTensor/SymmTensor/Tensor.

Usage

Example of the reference function object by using functions sub-dictionary in system/controlDict file: 

reference1
{
    // Mandatory entries (unmodifiable)
    type            reference;
    libs            (fieldFunctionObjects);

    // Mandatory (inherited) entries (runtime modifiable)
    field           <inpFfield>;

    // Optional entries (runtime modifiable)
    position    (0 0 0);
    scale       1.0;
    offset      0.0;
    interpolationScheme    cell;

    // Optional (inherited) entries
    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: reference word yes -
libs Library name: fieldFunctionObjects word yes -
field Name of the operand field word yes -
position Position to sample vector no <not used>
scale Scale value scalar no 1.0
offset Offset value scalar no 0.0
interpolationScheme Sampling scheme word no cell

The inherited entries are elaborated in:

Example by using the postProcess utility: 

postProcess -func "reference(<field>)"

Further information

Tutorial:

Source code:

History

  • Introduced in version v1806