∇

Description

The grad function object computes the gradient of an input field.

The operation is limited to scalar and vector volume or surface fields, and the output is a volume vector or tensor field.

Operands

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

Usage

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

grad1
{
    // Mandatory entries (unmodifiable)
    type            grad;
    libs            (fieldFunctionObjects);

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

    // 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: grad word yes -
libs Library name: fieldFunctionObjects word yes -
field Name of the operand field word yes -

The inherited entries are elaborated in:

Example by using the postProcess utility:

postProcess -func "grad(<field>)"

Further information

Tutorial:

Source code:

API:

History: