turbulentDFSEMInlet

Description

The turbulentDFSEMInlet is a synthesised-eddy based velocity inlet boundary condition to generate synthetic turbulence-alike time-series from a given set of turbulence statistics for LES and DES computations.

Usage

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

Boundary file

<patchName>
{
    type            patch;
    ...
}

Field file

<patchName>
{
    // Mandatory entries
    type            turbulentDFSEMInlet;
    delta           <scalar>;
    R               <PatchFunction1>;
    U               <PatchFunction1>;
    L               <PatchFunction1>;

        // e.g.
        // R        uniform (<Rxx> <Rxy> <Rxz> <Ryy> <Ryz> <Rzz>);
        // U        uniform (<Ux> <Uy> <Uz>);
        // L        uniform <L>;

    // Optional entries
    d               <scalar>;
    nCellPerEddy    <label>;
    kappa           <scalar>;
    Uref            <scalar>;
    Lref            <scalar>;
    scale           <scalar>;
    m               <scalar>;
    writeEddies     <bool>;

    // Inherited entries
    ...
}

where:

Property	Description	Type	Required	Default
type	Type name: turbulentDFSEMInlet	word	yes	-
delta	Characteristic length scale	scalar	yes	-
R	Reynolds-stress tensor field	PatchFunction1<symmTensor>	yes	-
U	Mean velocity field	PatchFunction1<vector>	yes	-
L	Integral-length scale field	PatchFunction1<scalar>	yes	-
d	Ratio of sum of eddy volumes to eddy box volume i.e. eddy density (fill fraction)	scalar	no	1.0
nCellPerEddy	Minimum eddy length in units of number of cells	label	no	5
kappa	von Karman constant	scalar	no	0.41
Uref	Normalisation factor for Reynolds-stress tensor and mean velocity	scalar	no	1.0
Lref	Normalisation factor for integral-length scale	scalar	no	1.0
scale	Heuristic scaling factor being applied on the normalisation factor C1	scalar	no	1.0
m	The power of V defined in C1	scalar	no	0.5
writeEddies	Flag to write eddies as OBJ file	bool	no	false

The inherited entries are elaborated in:

• Foam::fixedValueFvPatchField
• Foam::PatchFunction1
• Foam::PatchFunction1Types::MappedFile

• The delta value typically represents the characteristic scale of flow or flow domain, e.g. a channel half height for plane channel flows.
• nCellPerEddy and scale entries are heuristic entries which do not exist in the standard method, yet are necessary to reproduce the results published in the original journal paper.
• In the original journal paper, C1 in Eq. 11 is not dimensionless. It is not clear whether this dimensionality issue was intentional. To alleviate this matter, users can alter the input entry m, which is the power of the eddy-box volume defined in the C1, to obtain a dimensionless C1 coefficient. The default value of m is 0.5, which is the value stated in the original journal paper, and m=1/3 leads to a dimensionless C1.

Further information

Tutorial:

• planeChannel

Source code:

• turbulentDFSEMInlet

API:

• Foam::turbulentDFSEMInletFvPatchVectorField

History: Introduced in version v1606+