Description🔗

The turbulentInlet is a boundary condition that produces spatiotemporal-variant field by summing a set of pseudo-random numbers and a given spatiotemporal-invariant mean field. The field can be any type, e.g. scalarField. At a single point and time, all components are summed by the same random number, e.g. velocity components (u, v, w) are summed by the same random number, p; thus, output is (u+p, v+p, w+p).

The pseudo-random number generator obeys the probability density function of the uniform distribution constrained by the range [0:1]. The seed for the random number generator is hard-coded; therefore, it will produce the same sequence of random numbers at every execution.

\[x_p = (1 - \alpha) x_p^{n - 1} + \alpha (x_{ref} + c s R |x_{ref}|)\]

where:

Usage🔗

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

Boundary file🔗

<patchName>
{
    type             patch;
    ...
}

Field file🔗

<patchName>
{
    // Mandatory entries
    type             turbulentInlet;
    fluctuationScale <scalar>;               // the term `s` above
    referenceField   <scalarField>;          // the term `xRef` above

    // Optional entries
    alpha            <scalar>;               // the term `alpha` above

    // Inherited entries
    ...
}

where:

The inherited entries are elaborated in:

• fixedValueFvPatchField.H

• Random.H

• This boundary condition should not be used for DES or LES computations as a turbulent velocity inflow condition, because the BC will not produce turbulence-alike time-series, and will decay almost immediately downstream of the inlet boundary although its historical name suggests the opposite.
• Nevertheless, the BC may be still used for other applications, e.g. as a uniform-random noise source in aeroacoustics.

Further information🔗

Tutorial:

• $FOAM_TUTORIALS/incompressible/pisoFoam/LES/pitzDaily

Source code:

• $FOAM_SRC/finiteVolume/fields/fvPatchFields/derived/turbulentInlet

API:

• Foam::turbulentInletFvPatchField

History:

• Introduced in version 1.5