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Lagrangian: Rewrite of the particle tracking algorithm to function in

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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.
This commit is contained in:
Will Bainbridge
2017-04-28 08:03:44 +01:00
committed by Andrew Heather
parent dd3be135de
commit 743dea87d2
91 changed files with 3209 additions and 2443 deletions
Download Patch File Download Diff File Expand all files Collapse all files

8
src/sampling/sampledSet/face/faceOnlySet.C
View File

@ -56,13 +56,15 @@ bool Foam::faceOnlySet::trackToBoundary
{
particle::TrackingData<passiveParticleCloud> trackData(particleCloud);
const point& trackPt = singleParticle.position();
point trackPt = singleParticle.position();
while(true)
{
point oldPoint = trackPt;
singleParticle.trackToFace(end_, trackData);
singleParticle.trackToFace(end_ - start_, 0, trackData);
trackPt = singleParticle.position();
if (singleParticle.face() != -1 && mag(oldPoint - trackPt) > smallDist)
{
@ -78,7 +80,7 @@ bool Foam::faceOnlySet::trackToBoundary
// End reached
return false;
}
else if (singleParticle.onBoundary())
else if (singleParticle.onBoundaryFace())
{
// Boundary reached
return true;

23
src/sampling/sampledSet/polyLine/polyLineSet.C
View File

@ -2,7 +2,7 @@
========= |
\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
\\ / O peration |
\\ / A nd | Copyright (C) 2011-2016 OpenFOAM Foundation
\\ / A nd | Copyright (C) 2011-2017 OpenFOAM Foundation
\\/ M anipulation |
-------------------------------------------------------------------------------
License
@ -56,29 +56,16 @@ bool Foam::polyLineSet::trackToBoundary
{
particle::TrackingData<passiveParticleCloud> trackData(particleCloud);
// Alias
const point& trackPt = singleParticle.position();
while (true)
{
// Local geometry info
const vector offset = sampleCoords_[sampleI+1] - sampleCoords_[sampleI];
const scalar smallDist = mag(tol*offset);
point oldPos = trackPt;
label facei = -1;
do
{
singleParticle.stepFraction() = 0;
singleParticle.track(sampleCoords_[sampleI+1], trackData);
}
while
(
!singleParticle.onBoundary()
&& (mag(trackPt - oldPos) < smallDist)
);
singleParticle.track(offset, 0);
const point trackPt = singleParticle.position();
if (singleParticle.onBoundary())
if (singleParticle.onBoundaryFace())
{
//Info<< "trackToBoundary : reached boundary"
// << " trackPt:" << trackPt << endl;
@ -94,7 +81,7 @@ bool Foam::polyLineSet::trackToBoundary
// << endl;
samplingPts.append(trackPt);
samplingCells.append(singleParticle.cell());
samplingFaces.append(facei);
samplingFaces.append(singleParticle.face());
// trackPt is at sampleI+1
samplingCurveDist.append(1.0*(sampleI+1));

12
src/sampling/sampledSet/sampledSet/sampledSet.C
View File

@ -209,17 +209,25 @@ Foam::point Foam::sampledSet::pushIn
label tetPtI;
mesh().findTetFacePt(celli, facePt, tetFacei, tetPtI);
// This is the tolerance that was defined as a static constant of the
// particle class. It is no longer used by particle, following the switch to
// barycentric tracking. The only place in which the tolerance is now used
// is here. I'm not sure what the purpose of this code is, but it probably
// wants removing. It is doing tet-searches for a particle position. This
// should almost certainly be left to the particle class.
const scalar trackingCorrectionTol = 1e-5;
if (tetFacei == -1 || tetPtI == -1)
{
newPosition = facePt;
label trap(1.0/particle::trackingCorrectionTol + 1);
label trap(1.0/trackingCorrectionTol + 1);
label iterNo = 0;
do
{
newPosition += particle::trackingCorrectionTol*(cC - facePt);
newPosition += trackingCorrectionTol*(cC - facePt);
mesh().findTetFacePt
(

33
src/sampling/sampledSet/uniform/uniformSet.C
View File

@ -94,8 +94,7 @@ bool Foam::uniformSet::trackToBoundary
const vector smallVec = tol*offset;
const scalar smallDist = mag(smallVec);
// Alias
const point& trackPt = singleParticle.position();
point trackPt = singleParticle.position();
particle::TrackingData<passiveParticleCloud> trackData(particleCloud);
@ -153,32 +152,10 @@ bool Foam::uniformSet::trackToBoundary
<< " to:" << samplePt << endl;
}
point oldPos = trackPt;
label facei = -1;
do
{
singleParticle.stepFraction() = 0;
singleParticle.track(samplePt, trackData);
singleParticle.track(samplePt - trackPt, 0);
trackPt = singleParticle.position();
if (debug)
{
Pout<< "Result of tracking "
<< " trackPt:" << trackPt
<< " trackCelli:" << singleParticle.cell()
<< " trackFacei:" << singleParticle.face()
<< " onBoundary:" << singleParticle.onBoundary()
<< " samplePt:" << samplePt
<< " smallDist:" << smallDist
<< endl;
}
}
while
(
!singleParticle.onBoundary()
&& (mag(trackPt - oldPos) < smallDist)
);
if (singleParticle.onBoundary())
if (singleParticle.onBoundaryFace())
{
//Pout<< "trackToBoundary : reached boundary" << endl;
if (mag(trackPt - samplePt) < smallDist)
@ -188,7 +165,7 @@ bool Foam::uniformSet::trackToBoundary
// Reached samplePt on boundary
samplingPts.append(trackPt);
samplingCells.append(singleParticle.cell());
samplingFaces.append(facei);
samplingFaces.append(singleParticle.face());
samplingCurveDist.append(mag(trackPt - start_));
}