Added the interfacial pressure-work terms according to:
Ishii, M., Hibiki, T.,
Thermo-fluid dynamics of two-phase flow,
ISBN-10: 0-387-28321-8, 2006
While this is the most common approach to handling the interfacial
pressure-work it introduces numerical stability issues in regions of low
phase-fraction and rapid flow deformation. To alleviate this problem an
optional limiter may be applied to the pressure-work term in either of
the energy forms. This may specified in the
"thermophysicalProperties.<phase>" file, e.g.
pressureWorkAlphaLimit 1e-3;
which sets the pressure work term to 0 for phase-fractions below 1e-3.
For particularly unstable cases a limit of 1e-2 may be necessary.
Added 'READ_IF_PRESENT' option to support overriding of the default BCs
for complex problems requiring special treatment of Udm at boundaries.
Resolves bug-report http://bugs.openfoam.org/view.php?id=2317
In many publications and Euler-Euler codes the pressure-work term in the
total enthalpy is stated and implemented as -alpha*dp/dt rather than the
conservative form derived from the total internal energy equation
-d(alpha*p)/dt. In order for the enthalpy and internal energy equations
to be consistent this error/simplification propagates to the total
internal energy equation as a spurious additional term p*d(alpha)/dt
which is included in the OpenFOAM Euler-Euler solvers and causes
stability and conservation issues.
I have now re-derived the energy equations for multiphase flow from
first-principles and implemented in the reactingEulerFoam solvers the
correct conservative form of pressure-work in both the internal energy
and enthalpy equations.
Additionally an optional limiter may be applied to the pressure-work
term in either of the energy forms to avoid spurious fluctuations in the
phase temperature in regions where the phase-fraction -> 0. This may
specified in the "thermophysicalProperties.<phase>" file, e.g.
pressureWorkAlphaLimit 1e-3;
which sets the pressure work term to 0 for phase-fractions below 1e-3.
Previously the inlet flow of phase 1 (the phase solved for) is corrected
to match the inlet specification for that phase. However, if the second
phase is also constrained at inlets the inlet flux must also be
corrected to match the inlet specification.
- Write differences with respect to the specified dictionary
(or sub entry if -entry specified)
- Write the differences with respect to a template dictionary:
foamDictionary 0/U -diff $FOAM_ETC/templates/closedVolume/0/U
- Write the differences in boundaryField with respect to a
template dictionary:
foamDictionary 0/U -diff $FOAM_ETC/templates/closedVolume/0/U \
-entry boundaryField
Patch contributed by Mattijs Janssens
For example, to mesh a sphere with a single block the geometry is defined in the
blockMeshDict as a searchableSurface:
geometry
{
sphere
{
type searchableSphere;
centre (0 0 0);
radius 1;
}
}
The vertices, block topology and curved edges are defined in the usual
way, for example
v 0.5773502;
mv -0.5773502;
a 0.7071067;
ma -0.7071067;
vertices
(
($mv $mv $mv)
( $v $mv $mv)
( $v $v $mv)
($mv $v $mv)
($mv $mv $v)
( $v $mv $v)
( $v $v $v)
($mv $v $v)
);
blocks
(
hex (0 1 2 3 4 5 6 7) (10 10 10) simpleGrading (1 1 1)
);
edges
(
arc 0 1 (0 $ma $ma)
arc 2 3 (0 $a $ma)
arc 6 7 (0 $a $a)
arc 4 5 (0 $ma $a)
arc 0 3 ($ma 0 $ma)
arc 1 2 ($a 0 $ma)
arc 5 6 ($a 0 $a)
arc 4 7 ($ma 0 $a)
arc 0 4 ($ma $ma 0)
arc 1 5 ($a $ma 0)
arc 2 6 ($a $a 0)
arc 3 7 ($ma $a 0)
);
which will produce a mesh in which the block edges conform to the sphere
but the faces of the block lie somewhere between the original cube and
the spherical surface which is a consequence of the edge-based
transfinite interpolation.
Now the projection of the block faces to the geometry specified above
can also be specified:
faces
(
project (0 4 7 3) sphere
project (2 6 5 1) sphere
project (1 5 4 0) sphere
project (3 7 6 2) sphere
project (0 3 2 1) sphere
project (4 5 6 7) sphere
);
which produces a mesh that actually conforms to the sphere.
See OpenFOAM-dev/tutorials/mesh/blockMesh/sphere
This functionality is experimental and will undergo further development
and generalization in the future to support more complex surfaces,
feature edge specification and extraction etc. Please get involved if
you would like to see blockMesh become a more flexible block-structured
mesher.
Henry G. Weller, CFD Direct.
to handle the size of bubbles created by boiling. To be used in
conjunction with the alphatWallBoilingWallFunction boundary condition.
The IATE variant of the wallBoiling tutorial case is provided to
demonstrate the functionality:
tutorials/multiphase/reactingTwoPhaseEulerFoam/RAS/wallBoilingIATE
Contributed by Juho Peltola, VTT
Notable changes:
1. The same wall function is now used for both phases, but user must
specify phaseType ‘liquid’ or ‘vapor’
2. Runtime selectable submodels for:
- wall heat flux partitioning between the phases
- nucleation site density
- bubble departure frequency
- bubble departure diameter
3. An additional iteration loop for the wall boiling model in case
the initial guess for the wall temperature proves to be poor.
The wallBoiling tutorial has been updated to demonstrate this new functionality.
blockMesh -help
Usage: blockMesh [OPTIONS]
options:
-blockTopology write block edges and centres as .obj files
-case <dir> specify alternate case directory, default is the cwd
-dict <file> specify alternative dictionary for the blockMesh description
-noFunctionObjects
do not execute functionObjects
-region <name> specify alternative mesh region
-srcDoc display source code in browser
-doc display application documentation in browser
-help print the usage
Block description
For a given block, the correspondence between the ordering of
vertex labels and face labels is shown below.
For vertex numbering in the sequence 0 to 7 (block, centre):
faces 0 (f0) and 1 are left and right, respectively;
faces 2 and 3 are bottom and top;
and faces 4 and 5 are front the back:
4 ---- 5
f3 |\ |\ f5
| | 7 ---- 6 \
| 0 |--- 1 | \
| \| \| f4
f2 3 ---- 2
f0 ----- f1
Using: OpenFOAM-dev (see www.OpenFOAM.org)
Build: dev-dc59c63351e7
to ensure 'patchType' is set as specified.
Required substantial change to the organization of the reading of the
'value' entry requiring careful testing and there may be some residual
issues remaining. Please report any problems with the reading and
initialization of patch fields.
Resolves bug-report http://bugs.openfoam.org/view.php?id=2266
Renamed the original 'laminar' model to 'Stokes' to indicate it is a
linear stress model supporting both Newtonian and non-Newtonian
viscosity.
This general framework will support linear, non-linear, visco-elastic
etc. laminar transport models.
For backward compatibility the 'Stokes' laminar stress model can be
selected either the original 'laminar' 'simulationType'
specification in turbulenceProperties:
simulationType laminar;
or using the new more general 'laminarModel' specification:
simulationType laminar;
laminar
{
laminarModel Stokes;
}
which allows other laminar stress models to be selected.
Required to support LTS with the -postProcess option with sub-models dependent on ddt
terms during construction, in particular reactingTwoPhaseEulerFoam.
- There will be triangles rendered inside the mesh (when
surface-rendering), because one of the cell's triangles is defined
as a quadrangle in VTK_WEDGE.
- Therefore, this VTK_WEDGE representation is only used when
decomposing the mesh, otherwise the correct representation is done
by VTK_POLYHEDRON.
- Furthermore, using VTK_PYRAMID gave worse result, because it renders
2 triangles inside the mesh for the collapsed quadrangle, likely due
to mismatch with the adjacent cell's face.
- Using VTK_HEXAHEDRON was not tested in this iteration, given that it
should give even worse results, when compared to using VTK_PYRAMID.
Patch contributed by Bruno Santos
Resolves bug-report http://bugs.openfoam.org/view.php?id=2099
