From ea948340222155ff80d0c0d08d82645da77d1399 Mon Sep 17 00:00:00 2001
From: Kutalmis Bercin <kutalmis.bercin@esi-group.com>
Date: Thu, 12 Dec 2019 15:59:47 +0000
Subject: [PATCH] DOC: fix turbulentInlet BC header (#1100)
STYLE: add getOrDefault(), missing doc dashes
---
.../turbulentInletFvPatchField.C | 2 +-
.../turbulentInletFvPatchField.H | 64 +++++++++++++------
2 files changed, 45 insertions(+), 21 deletions(-)
diff --git a/src/finiteVolume/fields/fvPatchFields/derived/turbulentInlet/turbulentInletFvPatchField.C b/src/finiteVolume/fields/fvPatchFields/derived/turbulentInlet/turbulentInletFvPatchField.C
index 698a3277d22..996575e5e2e 100644
--- a/src/finiteVolume/fields/fvPatchFields/derived/turbulentInlet/turbulentInletFvPatchField.C
+++ b/src/finiteVolume/fields/fvPatchFields/derived/turbulentInlet/turbulentInletFvPatchField.C
@@ -57,7 +57,7 @@ Foam::turbulentInletFvPatchField<Type>::turbulentInletFvPatchField
ranGen_(label(0)),
fluctuationScale_(dict.get<Type>("fluctuationScale")),
referenceField_("referenceField", dict, p.size()),
- alpha_(dict.lookupOrDefault<scalar>("alpha", 0.1)),
+ alpha_(dict.getOrDefault<scalar>("alpha", 0.1)),
curTimeIndex_(-1)
{
if (dict.found("value"))
diff --git a/src/finiteVolume/fields/fvPatchFields/derived/turbulentInlet/turbulentInletFvPatchField.H b/src/finiteVolume/fields/fvPatchFields/derived/turbulentInlet/turbulentInletFvPatchField.H
index 018354b17ff..9119b7e2db0 100644
--- a/src/finiteVolume/fields/fvPatchFields/derived/turbulentInlet/turbulentInletFvPatchField.H
+++ b/src/finiteVolume/fields/fvPatchFields/derived/turbulentInlet/turbulentInletFvPatchField.H
@@ -30,44 +30,68 @@ Group
grpInletBoundaryConditions
Description
- This boundary condition generates a fluctuating inlet condition by adding
- a random component to a reference (mean) field.
+ This boundary condition 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.
\f[
- x_p = (1 - \alpha) x_p^{n-1} + \alpha (x_{ref} + s C_{RMS} x_{ref})
+ x_p = (1 - \alpha) x_p^{n - 1} + \alpha (x_{ref} + c s R |x_{ref}|)
\f]
-
where
\vartable
- x_p | patch values
- x_{ref} | reference patch values
+ x_p | patch field
+ x_{ref} | spatiotemporal-invariant patch scalar
n | time level
- \alpha | fraction of new random component added to previous time value
- C_{RMS} | RMS coefficient
- s | fluctuation scale
+ \alpha | a scalar attempting to build two-temporal-point correlations
+ by heuristically adding a fraction of the new random component
+ to the previous time patch field
+ c | a heuristic automatically calculated correction term
+ to compensate energy level losses due to the alpha scalar
+ R | pseudo-random number [HARD-CODED seed]
+ s | fluctuation scale (proportional to the xRef)
\endvartable
Usage
\table
- Property | Description | Required | Default value
+ Property | Description | Required | Default value
fluctuationScale | RMS fluctuation scale (fraction of mean) | yes |
- referenceField | reference (mean) field | yes |
- alpha | fraction of new random component added to previous| no| 0.1
+ referenceField | reference (mean) field | yes |
+ alpha | fraction of new random component added to previous | no | 0.1
\endtable
Example of the boundary condition specification:
\verbatim
<patchName>
{
- type turbulentInlet;
- fluctuationScale 0.1;
- referenceField uniform 10;
- alpha 0.1;
+ // Mandatory entries
+ type turbulentInlet;
+ fluctuationScale 0.1; // the term `s` above
+ referenceField uniform 10; // the term `xRef` above
+
+ // Optional entries
+ alpha 0.1; // the term `alpha` above
}
\endverbatim
-See also
+Note
+ 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.
+
+SeeAlso
Foam::fixedValueFvPatchField
SourceFiles
@@ -95,7 +119,7 @@ class turbulentInletFvPatchField
:
public fixedValueFvPatchField<Type>
{
- // Private data
+ // Private Data
//- Random number generator
Random ranGen_;
@@ -137,7 +161,7 @@ public:
);
//- Construct by mapping given turbulentInletFvPatchField
- // onto a new patch
+ //- onto a new patch
turbulentInletFvPatchField
(
const turbulentInletFvPatchField<Type>&,
@@ -181,7 +205,7 @@ public:
}
- // Member functions
+ // Member Functions
// Access
--
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