wallShearStress

Table of Contents

Description

The wallShearStress function object computes the wall-shear stress at selected wall patches.

\[ \vec \tau = \vec R \cdot \vec n \]

where

\( \vec \tau \) = Wall shear stress vector [m2/s2]
\( \vec R \) = Shear-stress symmetric tensor (retrieved from turbulence model)
\( \vec n \) = Patch normal vector (into the domain)

Operands

Operand Type Location
input - -
output file dat $FOAM_CASE/postProcessing/<FO>/<time>/<field>
output field volVectorField (only boundaryField) $FOAM_CASE/<time>/<outField>

Usage

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

wallShearStress1
{
    // Mandatory entries (unmodifiable)
    type            wallShearStress;
    libs            (fieldFunctionObjects);

    // Optional entries (runtime modifiable)
    patches         (<patch1> ... <patchN>); // (wall1 "(wall2|wall3)");

    // Optional (inherited) entries
    writePrecision  8;
    writeToFile     true;
    useUserTime     true;
    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: wallShearStress word yes -
libs Library name: fieldFunctionObjects word yes -
patches Names of operand patches wordList no all wall patches

The inherited entries are elaborated in:

Example by using the postProcess utility: 

<solver> -postProcess -func wallShearStress

Further information

Tutorial:

Source code:

History

  • Introduced in version v1606+