Requires the following changes to the corresponding entry in the fvOptions dictionary:
i. Use Tsol instead Tmelt as previously to define melting temperature in
isothermal phase change (for pure substance or eutectic mixture -> Tsol = Tliq);
ii. Optionally define new Tliq > Tsol to consider liquidus temperature in
non-isothermal phase change (for miscible mixture), where previous
defined Tsol defines solidus temperature;
iii. optionally define also alpha1e to consider max eutectic melt
fraction (that should be the percentage of solvent phase changed from
initial to eutectic liquid concentration) in partially isothermal (at
Tsol=Teutectic) and non-isothermal (from Tsol=Teutectic to Tliq) phase
change (for solid not miscible mixture) (alpha1e=0 -> pure substance;
alpha1e=1 -> eutectic mixture that is strictely not permitted).
Description
This source is designed to model the effect of solidification and melting
processes, e.g. windhield defrosting.
The isotherm phase change occurs at the melting temperature, \c Tsol (= \c
Tliq). The not isotherm phase change occurs between solidus and liquidus
temperature, \c Tsol < \c Tliq respectively, as long as the melt fraction is
greater than the max eutectic melt fraction, \c alpha1e (0 =
pure_substance, 1 = eutectic_mixture is not permitted) , i.e. eutectic to
initial solvent concentration difference, where a linear eutectic melt
fraction to temperature relation is considered - lever rule.
The presence of the solid phase in the flow field is incorporated into the
model as a momentum porosity contribution; the energy associated with the
phase change is added as an enthalpy contribution.
References:
\verbatim
Voller, V. R., & Prakash, C. (1987).
A fixed grid numerical modelling methodology for convection-diffusion
mushy region phase-change problems.
International Journal of Heat and Mass Transfer, 30(8), 1709-1719.
Swaminathan, C. R., & Voller, V. R. (1992).
A general enthalpy method for modeling solidification processes.
Metallurgical transactions B, 23(5), 651-664.
\endverbatim
The model generates the field \c \<name\>:alpha1 which can be visualised to
to show the melt distribution as a fraction [0-1].
Usage
Example usage:
\verbatim
solidificationMeltingSource1
{
type solidificationMeltingSource;
active yes;
selectionMode cellZone;
cellZone iceZone;
Tsol 273;
L 334000;
thermoMode thermo;
beta 50e-6;
rhoRef 800;
}
\endverbatim
Where:
\table
Property | Description | Required | Default value
Tsol | Solidus temperature [K] | yes |
Tliq | Liquidus temperature [K] | no | Tsol
alpha1e | Max eutectic melt fraction [0-1[ | no | 0
L | Latent heat of fusion [J/kg] | yes |
relax | Relaxation coefficient [0-1] | no | 0.9
thermoMode | Thermo mode [thermo|lookup] | yes |
rhoRef | Reference (solid) density [kg/m^3] | yes |
rho | Name of density field | no | rho
T | Name of temperature field | no | T
Cp | Name of specific heat field | no | Cp
U | Name of velocity field | no | U
phi | Name of flux field | no | phi
Cu | Model coefficient [1/s] | no | 100000
q | Model coefficient | no | 0.001
beta | Thermal expansion coefficient [1/K] | yes |
g | Accelerartion due to gravity | no |
\endtable
Patch contributed by Lorenzo Trevisan and integrated by CFD Direct.
Resolves patch request https://bugs.openfoam.org/view.php?id=2907
Specialized variants of the power law porosity and k epsilon turbulence models
developed to simulate atmospheric flow over forested and non-forested complex
terrain.
Class
Foam::powerLawLopesdaCosta
Description
Variant of the power law porosity model with spatially varying
drag coefficient
given by:
\f[
S = -\rho C_d \Sigma |U|^{(C_1 - 1)} U
\f]
where
\vartable
\Sigma | Porosity surface area per unit volume
C_d | Model linear coefficient
C_1 | Model exponent coefficient
\endvartable
Reference:
\verbatim
Costa, J. C. P. L. D. (2007).
Atmospheric flow over forested and non-forested complex terrain.
\endverbatim
Class
Foam::RASModels::kEpsilonLopesdaCosta
Description
Variant of the standard k-epsilon turbulence model with additional source
terms to handle the changes in turbulence in porous regions represented by
the powerLawLopesdaCosta porosity model.
Reference:
\verbatim
Costa, J. C. P. L. D. (2007).
Atmospheric flow over forested and non-forested complex terrain.
\endverbatim
The default model coefficients are
\verbatim
kEpsilonLopesdaCostaCoeffs
{
Cmu 0.09;
C1 1.44;
C2 1.92;
sigmak 1.0;
sigmaEps 1.3;
}
\endverbatim
Tutorial case to follow.
In early versions of OpenFOAM the scalar limits were simple macro replacements and the
names were capitalized to indicate this. The scalar limits are now static
constants which is a huge improvement on the use of macros and for consistency
the names have been changed to camel-case to indicate this and improve
readability of the code:
GREAT -> great
ROOTGREAT -> rootGreat
VGREAT -> vGreat
ROOTVGREAT -> rootVGreat
SMALL -> small
ROOTSMALL -> rootSmall
VSMALL -> vSmall
ROOTVSMALL -> rootVSmall
The original capitalized are still currently supported but their use is
deprecated.
The ramp function used to graduate the vertical damping force can now be
applied along a number of paths, rather than just one. The keywords
"origins" and "directions" can be used to define a list of paths.
verticalDamping1
{
type verticalDamping;
origins ((1200 0 0) (1200 100 0) (1200 -100 0));
directions ((1 0 0) (0 1 0) (0 -1 0));
// ...
}
The ramping function will be calculated along each of the paths defined
by the origin-direction pair, and the maximum of the calculated values
will be used.
The "origin" and "direction" keywords can still be used with non-list
values.
This work was supported by Jan Kaufmann and Jan Oberhagemann at DNV GL.
The onset of vertical damping can now be graduated over a distance. The
user specifies an origin and a direction along which the graduation
occurs, and a ramping function to specify the form of the graduation. An
example specification for the fvOption is:
verticalDamping1
{
type verticalDamping;
selectionMode all;
origin (1200 0 0);
direction (1 0 0);
ramp
{
type halfCosineRamp;
start 0;
duration 600;
}
lambda [0 0 -1 0 0 0 0] 1; // Damping coefficient
timeStart 0;
duration 1e6;
}
If the origin, direction or ramp entries are omitted then the fvOption
functions as before; applying the damping to the entire volume or the
specified cell set.
This work was supported by Jan Kaufmann and Jan Oberhagemann at DNV GL.
The outletPhaseMeanVelocity and waveVelocity boundary conditions now
support a "ramp" keyword, for which a function can be supplied to
gradually increase the input velocity. The following is an example
specification for an outlet patch:
outlet
{
type outletPhaseMeanVelocity;
Umean 2;
ramp
{
type quarterSineRamp;
start 0;
duration 5;
}
alpha alpha.water;
}
There is also a new velocityRamping function object, which provides a
matching force within the volume of the domain, so that the entire flow
is smoothly accelerated up to the operating condition. An example
specification is as follows:
velocityRamping
{
type velocityRamping;
active on;
selectionMode all;
U U;
velocity (-2 0 0);
ramp
{
type quarterSineRamp;
start 0;
duration 5;
}
}
These additions have been designed to facilitate a smoother startup of
ship simulations by avoiding the slamming transients associated with
initialising a uniform velocity field.
This work was supported by Jan Kaufmann and Jan Oberhagemann at DNV GL.
This fvOption applies an explicit damping force to components of the
vector field in the direction of gravity. Its intended purpose is to
damp the vertical motions of an interface in the region approaching an
outlet so that no reflections are generated. The level of damping is
specified by a coefficient, lambda, given in units of 1/s.
It can be enabled for a cellZone named "nearOutlet", by adding the
following entry to constant/fvOptions:
verticalDamping1
{
type verticalDamping;
selectionMode cellZone;
cellZone nearOutlet;
lambda [0 0 -1 0 0 0 0] 1;
timeStart 0;
duration 1e6;
}
This work was supported by Jan Kaufmann and Jan Oberhagemann at DNV GL.
except turbulence and lagrangian which will also be updated shortly.
For example in the nonNewtonianIcoFoam offsetCylinder tutorial the viscosity
model coefficients may be specified in the corresponding "<type>Coeffs"
sub-dictionary:
transportModel CrossPowerLaw;
CrossPowerLawCoeffs
{
nu0 [0 2 -1 0 0 0 0] 0.01;
nuInf [0 2 -1 0 0 0 0] 10;
m [0 0 1 0 0 0 0] 0.4;
n [0 0 0 0 0 0 0] 3;
}
BirdCarreauCoeffs
{
nu0 [0 2 -1 0 0 0 0] 1e-06;
nuInf [0 2 -1 0 0 0 0] 1e-06;
k [0 0 1 0 0 0 0] 0;
n [0 0 0 0 0 0 0] 1;
}
which allows a quick change between models, or using the simpler
transportModel CrossPowerLaw;
nu0 [0 2 -1 0 0 0 0] 0.01;
nuInf [0 2 -1 0 0 0 0] 10;
m [0 0 1 0 0 0 0] 0.4;
n [0 0 0 0 0 0 0] 3;
if quick switching between models is not required.
To support this more convenient parameter specification the inconsistent
specification of seedSampleSet in the streamLine and wallBoundedStreamLine
functionObjects had to be corrected from
// Seeding method.
seedSampleSet uniform; //cloud; //triSurfaceMeshPointSet;
uniformCoeffs
{
type uniform;
axis x; //distance;
// Note: tracks slightly offset so as not to be on a face
start (-1.001 -0.05 0.0011);
end (-1.001 -0.05 1.0011);
nPoints 20;
}
to the simpler
// Seeding method.
seedSampleSet
{
type uniform;
axis x; //distance;
// Note: tracks slightly offset so as not to be on a face
start (-1.001 -0.05 0.0011);
end (-1.001 -0.05 1.0011);
nPoints 20;
}
which also support the "<type>Coeffs" form
// Seeding method.
seedSampleSet
{
type uniform;
uniformCoeffs
{
axis x; //distance;
// Note: tracks slightly offset so as not to be on a face
start (-1.001 -0.05 0.0011);
end (-1.001 -0.05 1.0011);
nPoints 20;
}
}
For example the actuationDiskSource fvOption may now be specified
disk1
{
type actuationDiskSource;
fields (U);
selectionMode cellSet;
cellSet actuationDisk1;
diskDir (1 0 0); // Orientation of the disk
Cp 0.386;
Ct 0.58;
diskArea 40;
upstreamPoint (581849 4785810 1065);
}
rather than
disk1
{
type actuationDiskSource;
active on;
actuationDiskSourceCoeffs
{
fields (U);
selectionMode cellSet;
cellSet actuationDisk1;
diskDir (1 0 0); // Orientation of the disk
Cp 0.386;
Ct 0.58;
diskArea 40;
upstreamPoint (581849 4785810 1065);
}
}
but this form is supported for backward compatibility.
e.g. in tutorials/heatTransfer/buoyantSimpleFoam/externalCoupledCavity/0/T
hot
{
type externalCoupledTemperature;
commsDir "${FOAM_CASE}/comms";
file "data";
initByExternal yes;
log true;
value uniform 307.75; // 34.6 degC
}
Previously both 'file' and 'fileName' were used inconsistently in different
classes and given that there is no confusion or ambiguity introduced by using
the simpler 'file' rather than 'fileName' this change simplifies the use and
maintenance of OpenFOAM.
e.g. to avoid excessive unphysical velocities generated during slamming events in
incompressible VoF simulations
Usage
Example usage:
limitU
{
type limitVelocity;
active yes;
limitVelocityCoeffs
{
selectionMode all;
max 100;
}
}
Description
Constrain the field values within a specified region.
For example to set the turbulence properties within a porous region:
\verbatim
porosityTurbulence
{
type scalarFixedValueConstraint;
active yes;
scalarFixedValueConstraintCoeffs
{
selectionMode cellZone;
cellZone porosity;
fieldValues
{
k 30.7;
epsilon 1.5;
}
}
}
\endverbatim
See tutorials/compressible/rhoSimpleFoam/angledDuctExplicitFixedCoeff
constant/fvOptions for an example of this fvOption in action.
In most boundary conditions, fvOptions etc. required and optional fields
to be looked-up from the objectRegistry are selected by setting the
keyword corresponding to the standard field name in the BC etc. to the
appropriate name in the objectRegistry. Usually a default is provided
with sets the field name to the keyword name, e.g. in the
totalPressureFvPatchScalarField the velocity is selected by setting the
keyword 'U' to the appropriate name which defaults to 'U':
Property | Description | Required | Default value
U | velocity field name | no | U
phi | flux field name | no | phi
.
.
.
However, in some BCs and functionObjects and many fvOptions another
convention is used in which the field name keyword is appended by 'Name'
e.g.
Property | Description | Required | Default value
pName | pressure field name | no | p
UName | velocity field name | no | U
This difference in convention is unnecessary and confusing, hinders code
and dictionary reuse and complicates code maintenance. In this commit
the appended 'Name' is removed from the field selection keywords
standardizing OpenFOAM on the first convention above.
Generally fields and objects are selected using the 'field[s]' and
'object[s]' keywords but this was not consistent between all
functionObject, fvOptions etc. and now fixed by applying the following
renaming:
fieldName -> field
fieldNames -> fields
objectName -> object
objectNames -> objects
to have the prefix 'write' rather than 'output'
So outputTime() -> writeTime()
but 'outputTime()' is still supported for backward-compatibility.
Also removed the redundant secondary-writing functionality from Time
which has been superseded by the 'writeRegisteredObject' functionObject.
Rather than requiring each functionObject to handle failed construction
internally (using the active_ flag) the static member function "viable"
is provided which returns true if construction of the functionObject is
likely to be successful. Failed construction is then handled by the
wrapper-class which constructs the functionObject,
e.g. "OutputFilterFunctionObject".
These new names are more consistent and logical because:
primitiveField():
primitiveFieldRef():
Provides low-level access to the Field<Type> (primitive field)
without dimension or mesh-consistency checking. This should only be
used in the low-level functions where dimensional consistency is
ensured by careful programming and computational efficiency is
paramount.
internalField():
internalFieldRef():
Provides access to the DimensionedField<Type, GeoMesh> of values on
the internal mesh-type for which the GeometricField is defined and
supports dimension and checking and mesh-consistency checking.
