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TUT: update velocityDampingConstraint header (#942)

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STYLE: add getOrDefault(); const specifiers to velocityDampingConstraint
This commit is contained in:
Kutalmis Bercin
2019-12-17 13:31:28 +00:00
parent a3b5299b09
commit 7d252fa900
2 changed files with 33 additions and 23 deletions
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8
src/fvOptions/constraints/derived/velocityDampingConstraint/velocityDampingConstraint.C
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@ -55,7 +55,7 @@ void Foam::fv::velocityDampingConstraint::addDamping(fvMatrix<vector>& eqn)
// Note: we want to add // Note: we want to add
// deltaU/deltaT // deltaU/deltaT
// where deltaT is a local time scale: // where deltaT is a local time scale:
// U/(cbrt of volume) // U/(cbrt of volume)
// Since directly manipulating the diagonal we multiply by volume. // Since directly manipulating the diagonal we multiply by volume.
const scalarField& vol = mesh_.V(); const scalarField& vol = mesh_.V();
@ -66,10 +66,10 @@ void Foam::fv::velocityDampingConstraint::addDamping(fvMatrix<vector>& eqn)
forAll(U, cellI) forAll(U, cellI)
{ {
scalar magU = mag(U[cellI]); const scalar magU = mag(U[cellI]);
if (magU > UMax_) if (magU > UMax_)
{ {
scalar scale = sqr(Foam::cbrt(vol[cellI])); const scalar scale = sqr(Foam::cbrt(vol[cellI]));
diag[cellI] += scale*(magU-UMax_); diag[cellI] += scale*(magU-UMax_);
@ -129,7 +129,7 @@ bool Foam::fv::velocityDampingConstraint::read(const dictionary& dict)
if (!coeffs_.readIfPresent("UNames", fieldNames_)) if (!coeffs_.readIfPresent("UNames", fieldNames_))
{ {
fieldNames_.resize(1); fieldNames_.resize(1);
fieldNames_.first() = coeffs_.lookupOrDefault<word>("U", "U"); fieldNames_.first() = coeffs_.getOrDefault<word>("U", "U");
} }
applied_.setSize(fieldNames_.size(), false); applied_.setSize(fieldNames_.size(), false);

48
src/fvOptions/constraints/derived/velocityDampingConstraint/velocityDampingConstraint.H
View File

@ -31,28 +31,38 @@ Group
grpFvOptionsConstraints grpFvOptionsConstraints
Description Description
Constraint for velocity to dampen velocity fluctuations in Constraint on velocity field to dampen velocity fluctuations.
steady simulations
In case of velocity exceeding limit applies This constraint is primarily used to dampen velocity fluctuations in
a source sink to remove the excess velocity by adding a term the start-up phase of simulations. When the local velocity magnitude
that drives the velocity to 0 (note that we cannot use the old exceeds the user-supplied maximum value a sink term is activated in
term velocity since it most likely is already excessive). This the affected region to lower the velocity to the limiting value.
additional constraint is scaled with (U-UMax)/dt
where dt is a local time scale (= velocity/cellsize) so it switches off
if the velocity is below UMax.
Constraint described by: Usage
Example of functionality specification in \c fvOptions:
\verbatim
velocityDamper
{
// Mandatory entries
type velocityDampingConstraint;
UMax 200;
velocityDampingConstraintCoeffs // Optional entries
{ selectionMode all;
UMax 100; UNames (U); // names of given velocity fields
U U; // name of given velocity field if
//`UNames` is not present (default: U)
// Optional: name of velocity field (default: U) // Optional fvOptions entries
//U U; active true;
//UNames (U); }
} \endverbatim
Note
When active, this constraint manipulates the system of equations.
Users should ensure that it is not active when the case is converged
(steady-state) or during the period of interest (transient) to ensure
that its presence does not pollute the results.
SourceFiles SourceFiles
velocityDampingConstraint.C velocityDampingConstraint.C
@ -82,9 +92,9 @@ class velocityDampingConstraint
protected: protected:
// Protected data // Protected Data
//- Maximum velocity //- Maximum velocity magnitude
scalar UMax_; scalar UMax_;