Updated the tetrahedron and triangle classes to use the barycentric
primitives. Removed duplicate code for generating random positions in
tets and tris, and fixed bug in tri random position.
This tutorial demonstrates moving mesh and AMI with a Lagrangian cloud.
It is very slow, as interaction lists (required to compute collisions)
are not optimised for moving meshes. The simulation time has therefore
been made very short, so that it finishes in a reasonable time. The
mixer only completes a small fraction of a rotation in this time. This
is still sufficient to test tracking and collisions in the presence of
AMI and mesh motion.
In order to generate a convincing animation, however, the end time must
be increased and the simulation run for a number of days.
and the continuous-phase simulation type
For LTS and steady-state simulations the transient option does not need to be
provided as only steady-state tracking is appropriate. For transient running
the Lagrangian tracking may be steady or transient.
The evolution of a KinematicParcel happens in three stages; (1) tracking
across the cell, (2) interaction with the face or patch that has been
hit, and (3) clculation and and update of parcel and cell properties.
The KinematicParcel used to evolve in this order, as steps 1 and 2 were
part of the same lower level method. This meant that the update stage
was done after interacting with the face, meaning the parcel was not in
the cell that had just been tracked through, or, by means of a patch
interaction, had been modified such that it was no longer representative
of the track through the cell.
With the separation of stages 1 and 2 in the base class, it is now
possible to do the update stage before interacting with the face (i.e.,
proceeding in the order 1, 3, 2). This makes the state consistent for
the updates, and avoids the issues described.
Patch contributed by Timo Niemi, VTT.
This resolves bug report https://bugs.openfoam.org/view.php?id=2282
Particle collisions with ACMI patches are now handled. The hit detects
whether the location is within the overlap or the coupled region and
recurses, calling the hit routine appropriate for the region.
The low level tracking methods are now more consistently named. There is
now a distinction between tracking to a face and hitting it. Function
object side effects have been moved out of the base layer and into the
parcels on which they are meaningful.
The TrackData::switchProcessor flag was not being set for some of the
tracking steps made by the more complicated parcels. In the case that a
parcel starts the step already on a processor boundary, this sometimes
lead to the particle being transferred back and forth indefinitely. The
flag is now explicitly set in all cases.
Tracking through an inverted region of the mesh happens in a reversed
direction relative to a non-inverted region. Usually, this allows the
tracking to propagate normally, regardless of the sign of the space.
However, in rare cases, it is possible for a straight trajectory to form
a closed loop through both positive and negative regions. This causes
the tracking to loop indefinitely.
To fix this, the displacement through inverted regions has been
artifically increased by a small amount (1% at the moment). This has the
effect that the change in track fraction over the negative part of the
loop no longer exactly cancels the change over the positive part, and
the track therefore terminates.
The KinematicCloud::patchData method has been made consistent on moving
meshes and/or when the time-step is being sub-cycled.
It has also been altered to calculate the normal component of a moving
patch's velocity directly from the point motions. This prevents an
infinite loop occuring due to inconsistency between the velocity used to
calculate a rebound and that used when tracking.
Some minor style improvements to the particle class have also been made.
The particle collector was collecting some particles twice due to a
tolerance extending the tracked path. This has been removed. The new
tracking algorithm does not generate the same sorts of spurious
tolerance-scale motions that the old one did, so this extension of the
tracking path is unnecessary.
Some particles were also not being collected at all as they were hitting
a diagonal of the collection polygon and registering as not having hit
either of the adjacent triangles. The hit criteria has been rewritten. A
hit now occurs when the normals of the triangles created by joining the
intersection point with the polygon edges are all in the same direction
as the overall polygon normal. This calculation is not affected by the
polygon's diagonals.
The issue was raised by, and resolved with support from, Karl Meredith
at FM Global.
This resolves bug-report https://bugs.openfoam.org/view.php?id=2595
This change changes the point-tetIndices-face interpolation function
method to take barycentric-tetIndices-face arguments instead. This
function is, at present, only used for interpolating Eulerian data to
Lagrangian particles.
This change prevents an inefficiency in cellPointInterpolation whereby
the position of the particle is calculated from it's barycentric
coordinates, before immediately being converted back to barycentric
coordinates to perform the interpolation.
The averaging methods now take the particle barycentric coordinates as
inputs rather than global positions. This change significantly optimises
Dual averaging, which is the most commonly used method. The run time of
the lagrangian/MPPICFoam/Goldschmidt tutorial has been reduced by a
factor of about two.
now possible with level-sets as well as planes. Removed tetPoints class
as this wasn't really used anywhere except for the old tet-cutting
routines. Restored tetPointRef.H to be consistent with other primitive
shapes. Re-wrote tet-overlap mapping in terms of the new cutting.
terms of the local barycentric coordinates of the current tetrahedron,
rather than the global coordinate system.
Barycentric tracking works on any mesh, irrespective of mesh quality.
Particles do not get "lost", and tracking does not require ad-hoc
"corrections" or "rescues" to function robustly, because the calculation
of particle-face intersections is unambiguous and reproducible, even at
small angles of incidence.
Each particle position is defined by topology (i.e. the decomposed tet
cell it is in) and geometry (i.e. where it is in the cell). No search
operations are needed on restart or reconstruct, unlike when particle
positions are stored in the global coordinate system.
The particle positions file now contains particles' local coordinates
and topology, rather than the global coordinates and cell. This change
to the output format is not backwards compatible. Existing cases with
Lagrangian data will not restart, but they will still run from time
zero without any modification. This change was necessary in order to
guarantee that the loaded particle is valid, and therefore
fundamentally prevent "loss" and "search-failure" type bugs (e.g.,
2517, 2442, 2286, 1836, 1461, 1341, 1097).
The tracking functions have also been converted to function in terms
of displacement, rather than end position. This helps remove floating
point error issues, particularly towards the end of a tracking step.
Wall bounded streamlines have been removed. The implementation proved
incompatible with the new tracking algorithm. ParaView has a surface
LIC plugin which provides equivalent, or better, functionality.
Additionally, bug report <https://bugs.openfoam.org/view.php?id=2517>
is resolved by this change.
- previous only checked for clouds at the last instance and only
detected lagrangian fields from the first cloud.
Now check for clouds at all instances and detect all of their fields
as well.
- affects surfaceFieldValue, volFieldValue.
Use 'none' (if desired) to explicitly suppress the weightField, but
generally better to use a different operation.
