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Description

The fixedShearStress is boundary condition that sets a user-defined shear stress constant and uniform across a given patch by using the expression:

\[\tau_0 = -\nu_{eff} \frac{d\u}{dn}\]

where:

Property Description
\(\tau\) Shear stress
\(\u\) Velocity
\(\nu_{eff}\) Effective viscosity
\(n\) Wall normal direction

Usage

The condition requires entries in both the boundary and field files.

Boundary file 

<patchName>
{
    type            wall;
    ...
}

Field file 

<patchName>
{
    // Mandatory entries
    type            fixedShearStress;

    // Optional entries
    tau             <vector>;

    // Inherited entries
    ...
}

where:

Property Description Type Required Default
type Type name: fixedShearStress word yes -
tau Type name: fixedShearStress vector no Zero

The inherited entries are elaborated in:

  • fixedValueFvPatchField.H

Further information

Tutorial:

Source code:

API:

History:

  • Introduced in version 2.2.2