ENH: Transferring momentOfInertia calc from utils to meshTools lib.

Adding mesh cell inertia calc.
This commit is contained in:
graham
2010-12-15 17:46:15 +00:00
parent cde4e66674
commit aa15f4479c
8 changed files with 464 additions and 805 deletions

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@ -1,5 +1,6 @@
EXE_INC = \ EXE_INC = \
-I$(LIB_SRC)/meshTools/lnInclude -I$(LIB_SRC)/meshTools/lnInclude \
-I$(LIB_SRC)/triSurface/lnInclude
EXE_LIBS = \ EXE_LIBS = \
-lmeshTools -lmeshTools

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@ -26,180 +26,38 @@ Application
Description Description
Calculates the inertia tensor and principal axes and moments of a Calculates the inertia tensor and principal axes and moments of a
test face and tetrahedron. test face, tetrahedron and mesh.
\*---------------------------------------------------------------------------*/ \*---------------------------------------------------------------------------*/
#include "argList.H"
#include "Time.H"
#include "polyMesh.H"
#include "ListOps.H" #include "ListOps.H"
#include "face.H" #include "face.H"
#include "tetPointRef.H" #include "tetPointRef.H"
#include "triFaceList.H" #include "triFaceList.H"
#include "OFstream.H" #include "OFstream.H"
#include "meshTools.H" #include "meshTools.H"
#include "momentOfInertia.H"
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
using namespace Foam; using namespace Foam;
void massPropertiesSolid
(
const pointField& pts,
const triFaceList triFaces,
scalar density,
scalar& mass,
vector& cM,
tensor& J
)
{
// Reimplemented from: Wm4PolyhedralMassProperties.cpp
// File Version: 4.10.0 (2009/11/18)
// Geometric Tools, LC
// Copyright (c) 1998-2010
// Distributed under the Boost Software License, Version 1.0.
// http://www.boost.org/LICENSE_1_0.txt
// http://www.geometrictools.com/License/Boost/LICENSE_1_0.txt
// Boost Software License - Version 1.0 - August 17th, 2003
// Permission is hereby granted, free of charge, to any person or
// organization obtaining a copy of the software and accompanying
// documentation covered by this license (the "Software") to use,
// reproduce, display, distribute, execute, and transmit the
// Software, and to prepare derivative works of the Software, and
// to permit third-parties to whom the Software is furnished to do
// so, all subject to the following:
// The copyright notices in the Software and this entire
// statement, including the above license grant, this restriction
// and the following disclaimer, must be included in all copies of
// the Software, in whole or in part, and all derivative works of
// the Software, unless such copies or derivative works are solely
// in the form of machine-executable object code generated by a
// source language processor.
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
// OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, TITLE AND
// NON-INFRINGEMENT. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR
// ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE FOR ANY DAMAGES OR
// OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
// USE OR OTHER DEALINGS IN THE SOFTWARE.
const scalar r6 = 1.0/6.0;
const scalar r24 = 1.0/24.0;
const scalar r60 = 1.0/60.0;
const scalar r120 = 1.0/120.0;
// order: 1, x, y, z, x^2, y^2, z^2, xy, yz, zx
scalarField integrals(10, 0.0);
forAll(triFaces, i)
{
const triFace& tri(triFaces[i]);
// vertices of triangle i
vector v0 = pts[tri[0]];
vector v1 = pts[tri[1]];
vector v2 = pts[tri[2]];
// cross product of edges
vector eA = v1 - v0;
vector eB = v2 - v0;
vector n = eA ^ eB;
// compute integral terms
scalar tmp0, tmp1, tmp2;
scalar f1x, f2x, f3x, g0x, g1x, g2x;
tmp0 = v0.x() + v1.x();
f1x = tmp0 + v2.x();
tmp1 = v0.x()*v0.x();
tmp2 = tmp1 + v1.x()*tmp0;
f2x = tmp2 + v2.x()*f1x;
f3x = v0.x()*tmp1 + v1.x()*tmp2 + v2.x()*f2x;
g0x = f2x + v0.x()*(f1x + v0.x());
g1x = f2x + v1.x()*(f1x + v1.x());
g2x = f2x + v2.x()*(f1x + v2.x());
scalar f1y, f2y, f3y, g0y, g1y, g2y;
tmp0 = v0.y() + v1.y();
f1y = tmp0 + v2.y();
tmp1 = v0.y()*v0.y();
tmp2 = tmp1 + v1.y()*tmp0;
f2y = tmp2 + v2.y()*f1y;
f3y = v0.y()*tmp1 + v1.y()*tmp2 + v2.y()*f2y;
g0y = f2y + v0.y()*(f1y + v0.y());
g1y = f2y + v1.y()*(f1y + v1.y());
g2y = f2y + v2.y()*(f1y + v2.y());
scalar f1z, f2z, f3z, g0z, g1z, g2z;
tmp0 = v0.z() + v1.z();
f1z = tmp0 + v2.z();
tmp1 = v0.z()*v0.z();
tmp2 = tmp1 + v1.z()*tmp0;
f2z = tmp2 + v2.z()*f1z;
f3z = v0.z()*tmp1 + v1.z()*tmp2 + v2.z()*f2z;
g0z = f2z + v0.z()*(f1z + v0.z());
g1z = f2z + v1.z()*(f1z + v1.z());
g2z = f2z + v2.z()*(f1z + v2.z());
// update integrals
integrals[0] += n.x()*f1x;
integrals[1] += n.x()*f2x;
integrals[2] += n.y()*f2y;
integrals[3] += n.z()*f2z;
integrals[4] += n.x()*f3x;
integrals[5] += n.y()*f3y;
integrals[6] += n.z()*f3z;
integrals[7] += n.x()*(v0.y()*g0x + v1.y()*g1x + v2.y()*g2x);
integrals[8] += n.y()*(v0.z()*g0y + v1.z()*g1y + v2.z()*g2y);
integrals[9] += n.z()*(v0.x()*g0z + v1.x()*g1z + v2.x()*g2z);
}
integrals[0] *= r6;
integrals[1] *= r24;
integrals[2] *= r24;
integrals[3] *= r24;
integrals[4] *= r60;
integrals[5] *= r60;
integrals[6] *= r60;
integrals[7] *= r120;
integrals[8] *= r120;
integrals[9] *= r120;
// mass
mass = integrals[0];
// center of mass
cM = vector(integrals[1], integrals[2], integrals[3])/mass;
// inertia relative to origin
J.xx() = integrals[5] + integrals[6];
J.xy() = -integrals[7];
J.xz() = -integrals[9];
J.yx() = J.xy();
J.yy() = integrals[4] + integrals[6];
J.yz() = -integrals[8];
J.zx() = J.xz();
J.zy() = J.yz();
J.zz() = integrals[4] + integrals[5];
// inertia relative to center of mass
J -= mass*((cM & cM)*I - cM*cM);
// Apply density
mass *= density;
J *= density;
}
int main(int argc, char *argv[]) int main(int argc, char *argv[])
{ {
argList::addOption
(
"cell",
"label",
"cell to use for inertia calculation, defaults to 0"
);
#include "setRootCase.H"
#include "createTime.H"
#include "createPolyMesh.H"
scalar density = 1.0; scalar density = 1.0;
{ {
@ -286,16 +144,7 @@ int main(int argc, char *argv[])
vector cM = vector::zero; vector cM = vector::zero;
tensor J = tensor::zero; tensor J = tensor::zero;
massPropertiesSolid momentOfInertia::massPropertiesSolid(pts, tetFaces, density, m, cM, J);
(
pts,
tetFaces,
density,
m,
cM,
J
);
vector eVal = eigenValues(J); vector eVal = eigenValues(J);
@ -344,7 +193,50 @@ int main(int argc, char *argv[])
{ {
str << "l " << nPts + 1 << ' ' << i + 1 << endl; str << "l " << nPts + 1 << ' ' << i + 1 << endl;
} }
}
{
const label cellI = args.optionLookupOrDefault("cell", 0);
tensorField mI = momentOfInertia::meshInertia(mesh);
tensor& J = mI[cellI];
vector eVal = eigenValues(J);
Info<< nl
<< "Inertia tensor of cell " << cellI << " " << J << nl
<< "eigenValues (principal moments) " << eVal << endl;
J /= cmptMax(eVal);
tensor eVec = eigenVectors(J);
Info<< "eigenVectors (principal axes, from normalised inertia) " << eVec
<< endl;
OFstream str("cell_" + name(cellI) + "_inertia.obj");
Info<< nl << "Writing scaled principal axes of cell " << cellI << " to "
<< str.name() << endl;
const point& cC = mesh.cellCentres()[cellI];
scalar scale = mag
(
(cC - mesh.faceCentres()[mesh.cells()[cellI][0]])
/eVal.component(findMin(eVal))
);
meshTools::writeOBJ(str, cC);
meshTools::writeOBJ(str, cC + scale*eVal.x()*eVec.x());
meshTools::writeOBJ(str, cC + scale*eVal.y()*eVec.y());
meshTools::writeOBJ(str, cC + scale*eVal.z()*eVec.z());
for (label i = 1; i < 4; i++)
{
str << "l " << 1 << ' ' << i + 1 << endl;
}
} }
Info<< nl << "End" << nl << endl; Info<< nl << "End" << nl << endl;

View File

@ -33,9 +33,6 @@ Description
#include "argList.H" #include "argList.H"
#include "ListOps.H" #include "ListOps.H"
#include "face.H"
#include "tetPointRef.H"
#include "triFaceList.H"
#include "triSurface.H" #include "triSurface.H"
#include "OFstream.H" #include "OFstream.H"
#include "meshTools.H" #include "meshTools.H"
@ -43,242 +40,12 @@ Description
#include "transform.H" #include "transform.H"
#include "IOmanip.H" #include "IOmanip.H"
#include "Pair.H" #include "Pair.H"
#include "momentOfInertia.H"
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
using namespace Foam; using namespace Foam;
void massPropertiesSolid
(
const pointField& pts,
const triFaceList& triFaces,
scalar density,
scalar& mass,
vector& cM,
tensor& J
)
{
// Reimplemented from: Wm4PolyhedralMassProperties.cpp
// File Version: 4.10.0 (2009/11/18)
// Geometric Tools, LC
// Copyright (c) 1998-2010
// Distributed under the Boost Software License, Version 1.0.
// http://www.boost.org/LICENSE_1_0.txt
// http://www.geometrictools.com/License/Boost/LICENSE_1_0.txt
// Boost Software License - Version 1.0 - August 17th, 2003
// Permission is hereby granted, free of charge, to any person or
// organization obtaining a copy of the software and accompanying
// documentation covered by this license (the "Software") to use,
// reproduce, display, distribute, execute, and transmit the
// Software, and to prepare derivative works of the Software, and
// to permit third-parties to whom the Software is furnished to do
// so, all subject to the following:
// The copyright notices in the Software and this entire
// statement, including the above license grant, this restriction
// and the following disclaimer, must be included in all copies of
// the Software, in whole or in part, and all derivative works of
// the Software, unless such copies or derivative works are solely
// in the form of machine-executable object code generated by a
// source language processor.
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
// OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, TITLE AND
// NON-INFRINGEMENT. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR
// ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE FOR ANY DAMAGES OR
// OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
// USE OR OTHER DEALINGS IN THE SOFTWARE.
const scalar r6 = 1.0/6.0;
const scalar r24 = 1.0/24.0;
const scalar r60 = 1.0/60.0;
const scalar r120 = 1.0/120.0;
// order: 1, x, y, z, x^2, y^2, z^2, xy, yz, zx
scalarField integrals(10, 0.0);
forAll(triFaces, i)
{
const triFace& tri(triFaces[i]);
// vertices of triangle i
vector v0 = pts[tri[0]];
vector v1 = pts[tri[1]];
vector v2 = pts[tri[2]];
// cross product of edges
vector eA = v1 - v0;
vector eB = v2 - v0;
vector n = eA ^ eB;
// compute integral terms
scalar tmp0, tmp1, tmp2;
scalar f1x, f2x, f3x, g0x, g1x, g2x;
tmp0 = v0.x() + v1.x();
f1x = tmp0 + v2.x();
tmp1 = v0.x()*v0.x();
tmp2 = tmp1 + v1.x()*tmp0;
f2x = tmp2 + v2.x()*f1x;
f3x = v0.x()*tmp1 + v1.x()*tmp2 + v2.x()*f2x;
g0x = f2x + v0.x()*(f1x + v0.x());
g1x = f2x + v1.x()*(f1x + v1.x());
g2x = f2x + v2.x()*(f1x + v2.x());
scalar f1y, f2y, f3y, g0y, g1y, g2y;
tmp0 = v0.y() + v1.y();
f1y = tmp0 + v2.y();
tmp1 = v0.y()*v0.y();
tmp2 = tmp1 + v1.y()*tmp0;
f2y = tmp2 + v2.y()*f1y;
f3y = v0.y()*tmp1 + v1.y()*tmp2 + v2.y()*f2y;
g0y = f2y + v0.y()*(f1y + v0.y());
g1y = f2y + v1.y()*(f1y + v1.y());
g2y = f2y + v2.y()*(f1y + v2.y());
scalar f1z, f2z, f3z, g0z, g1z, g2z;
tmp0 = v0.z() + v1.z();
f1z = tmp0 + v2.z();
tmp1 = v0.z()*v0.z();
tmp2 = tmp1 + v1.z()*tmp0;
f2z = tmp2 + v2.z()*f1z;
f3z = v0.z()*tmp1 + v1.z()*tmp2 + v2.z()*f2z;
g0z = f2z + v0.z()*(f1z + v0.z());
g1z = f2z + v1.z()*(f1z + v1.z());
g2z = f2z + v2.z()*(f1z + v2.z());
// update integrals
integrals[0] += n.x()*f1x;
integrals[1] += n.x()*f2x;
integrals[2] += n.y()*f2y;
integrals[3] += n.z()*f2z;
integrals[4] += n.x()*f3x;
integrals[5] += n.y()*f3y;
integrals[6] += n.z()*f3z;
integrals[7] += n.x()*(v0.y()*g0x + v1.y()*g1x + v2.y()*g2x);
integrals[8] += n.y()*(v0.z()*g0y + v1.z()*g1y + v2.z()*g2y);
integrals[9] += n.z()*(v0.x()*g0z + v1.x()*g1z + v2.x()*g2z);
}
integrals[0] *= r6;
integrals[1] *= r24;
integrals[2] *= r24;
integrals[3] *= r24;
integrals[4] *= r60;
integrals[5] *= r60;
integrals[6] *= r60;
integrals[7] *= r120;
integrals[8] *= r120;
integrals[9] *= r120;
// mass
mass = integrals[0];
// center of mass
cM = vector(integrals[1], integrals[2], integrals[3])/mass;
// inertia relative to origin
J.xx() = integrals[5] + integrals[6];
J.xy() = -integrals[7];
J.xz() = -integrals[9];
J.yx() = J.xy();
J.yy() = integrals[4] + integrals[6];
J.yz() = -integrals[8];
J.zx() = J.xz();
J.zy() = J.yz();
J.zz() = integrals[4] + integrals[5];
// inertia relative to center of mass
J -= mass*((cM & cM)*I - cM*cM);
// Apply density
mass *= density;
J *= density;
}
void massPropertiesShell
(
const pointField& pts,
const triFaceList& triFaces,
scalar density,
scalar& mass,
vector& cM,
tensor& J
)
{
// Reset properties for accumulation
mass = 0.0;
cM = vector::zero;
J = tensor::zero;
// Find centre of mass
forAll(triFaces, i)
{
const triFace& tri(triFaces[i]);
triPointRef t
(
pts[tri[0]],
pts[tri[1]],
pts[tri[2]]
);
scalar triMag = t.mag();
cM += triMag*t.centre();
mass += triMag;
}
cM /= mass;
mass *= density;
// Find inertia around centre of mass
forAll(triFaces, i)
{
const triFace& tri(triFaces[i]);
J += triPointRef
(
pts[tri[0]],
pts[tri[1]],
pts[tri[2]]
).inertia(cM, density);
}
}
tensor applyParallelAxisTheorem
(
scalar m,
const vector& cM,
const tensor& J,
const vector& refPt
)
{
// The displacement vector (refPt = cM) is the displacement of the
// new reference point from the centre of mass of the body that
// the inertia tensor applies to.
vector d = (refPt - cM);
return J + m*((d & d)*I - d*d);
}
int main(int argc, char *argv[]) int main(int argc, char *argv[])
{ {
argList::addNote argList::addNote
@ -321,40 +88,17 @@ int main(int argc, char *argv[])
triSurface surf(surfFileName); triSurface surf(surfFileName);
triFaceList faces(surf.size());
forAll(surf, i)
{
faces[i] = triFace(surf[i]);
}
scalar m = 0.0; scalar m = 0.0;
vector cM = vector::zero; vector cM = vector::zero;
tensor J = tensor::zero; tensor J = tensor::zero;
if (args.optionFound("shellProperties")) if (args.optionFound("shellProperties"))
{ {
massPropertiesShell momentOfInertia::massPropertiesShell(surf, density, m, cM, J);
(
surf.points(),
faces,
density,
m,
cM,
J
);
} }
else else
{ {
massPropertiesSolid momentOfInertia::massPropertiesSolid(surf, density, m, cM, J);
(
surf.points(),
faces,
density,
m,
cM,
J
);
} }
if (m < 0) if (m < 0)
@ -583,7 +327,7 @@ int main(int argc, char *argv[])
showTransform = false; showTransform = false;
} }
Info<< nl << setprecision(10) Info<< nl << setprecision(12)
<< "Density: " << density << nl << "Density: " << density << nl
<< "Mass: " << m << nl << "Mass: " << m << nl
<< "Centre of mass: " << cM << nl << "Centre of mass: " << cM << nl
@ -615,7 +359,7 @@ int main(int argc, char *argv[])
if (calcAroundRefPt) if (calcAroundRefPt)
{ {
Info<< nl << "Inertia tensor relative to " << refPt << ": " << nl Info<< nl << "Inertia tensor relative to " << refPt << ": " << nl
<< applyParallelAxisTheorem(m, cM, J, refPt) << momentOfInertia::applyParallelAxisTheorem(m, cM, J, refPt)
<< endl; << endl;
} }

View File

@ -41,6 +41,7 @@ SourceFiles
#include "tetPointRef.H" #include "tetPointRef.H"
#include "triPointRef.H" #include "triPointRef.H"
#include "polyMesh.H" #include "polyMesh.H"
#include "triFace.H"
#include "face.H" #include "face.H"
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
@ -146,6 +147,10 @@ public:
// mesh face for this tet from the supplied mesh // mesh face for this tet from the supplied mesh
inline triPointRef faceTri(const polyMesh& mesh) const; inline triPointRef faceTri(const polyMesh& mesh) const;
//- Return the point indices corresponding to the tri on the mesh
// face for this tet from the supplied mesh
inline triFace faceTriIs(const polyMesh& mesh) const;
//- Return the geometry corresponding to the tri on the //- Return the geometry corresponding to the tri on the
// mesh face for this tet from the supplied mesh using // mesh face for this tet from the supplied mesh using
// the old position // the old position

View File

@ -122,6 +122,21 @@ Foam::triPointRef Foam::tetIndices::faceTri(const polyMesh& mesh) const
} }
Foam::triFace Foam::tetIndices::faceTriIs(const polyMesh& mesh) const
{
const faceList& pFaces = mesh.faces();
const Foam::face& f = pFaces[faceI_];
return triFace
(
f[faceBasePtI_],
f[facePtAI_],
f[facePtBI_]
);
}
Foam::triPointRef Foam::tetIndices::oldFaceTri(const polyMesh& mesh) const Foam::triPointRef Foam::tetIndices::oldFaceTri(const polyMesh& mesh) const
{ {
const pointField& oldPPts = mesh.oldPoints(); const pointField& oldPPts = mesh.oldPoints();

View File

@ -127,6 +127,7 @@ $(cellZoneSources)/setToCellZone/setToCellZone.C
pointZoneSources = sets/pointZoneSources pointZoneSources = sets/pointZoneSources
$(pointZoneSources)/setToPointZone/setToPointZone.C $(pointZoneSources)/setToPointZone/setToPointZone.C
momentOfInertia/momentOfInertia.C
surfaceSets/surfaceSets.C surfaceSets/surfaceSets.C

View File

@ -21,382 +21,328 @@ License
You should have received a copy of the GNU General Public License You should have received a copy of the GNU General Public License
along with OpenFOAM. If not, see <http://www.gnu.org/licenses/>. along with OpenFOAM. If not, see <http://www.gnu.org/licenses/>.
Class \*---------------------------------------------------------------------------*/
momentOfInertia
Description
Reimplementation of volInt.c by Brian Mirtich.
* mirtich@cs.berkeley.edu *
* http://www.cs.berkeley.edu/~mirtich *
-------------------------------------------------------------------------------
*/
#include "momentOfInertia.H" #include "momentOfInertia.H"
//#include "pyramidPointFaceRef.H"
// * * * * * * * * * * * * * Private Member Functions * * * * * * * * * * * // // * * * * * * * * * * * * * Static Member Functions * * * * * * * * * * * * //
//Foam::tensor Foam::momentOfInertia void Foam::momentOfInertia::massPropertiesSolid
//(
// const pointField& points,
// const faceList& faces,
// const cell& cFaces,
// const point& cc
//)
//{
// tensor t(tensor::zero);
//
// forAll(cFaces, i)
// {
// const face& f = faces[cFaces[i]];
//
// scalar pyrVol = pyramidPointFaceRef(f, cc).mag(points);
//
// vector pyrCentre = pyramidPointFaceRef(f, cc).centre(points);
//
// vector d = pyrCentre - cc;
//
// t.xx() += pyrVol*(sqr(d.y()) + sqr(d.z()));
// t.yy() += pyrVol*(sqr(d.x()) + sqr(d.z()));
// t.zz() += pyrVol*(sqr(d.x()) + sqr(d.y()));
//
// t.xy() -= pyrVol*d.x()*d.y();
// t.xz() -= pyrVol*d.x()*d.z();
// t.yz() -= pyrVol*d.y()*d.z();
// }
//
// // Symmetric
// t.yx() = t.xy();
// t.zx() = t.xz();
// t.zy() = t.yz();
//
// return t;
//}
#define sqr(x) ((x)*(x))
#define pow3(x) ((x)*(x)*(x))
// compute various integrations over projection of face
void Foam::compProjectionIntegrals
( (
const pointField& points, const pointField& pts,
const face& f, const triFaceList& triFaces,
const direction A, scalar density,
const direction B, scalar& mass,
vector& cM,
scalar& P1,
scalar& Pa,
scalar& Pb,
scalar& Paa,
scalar& Pab,
scalar& Pbb,
scalar& Paaa,
scalar& Paab,
scalar& Pabb,
scalar& Pbbb
)
{
P1 = Pa = Pb = Paa = Pab = Pbb = Paaa = Paab = Pabb = Pbbb = 0.0;
forAll(f, i)
{
scalar a0 = points[f[i]][A];
scalar b0 = points[f[i]][B];
scalar a1 = points[f[(i+1) % f.size()]][A];
scalar b1 = points[f[(i+1) % f.size()]][B];
scalar da = a1 - a0;
scalar db = b1 - b0;
scalar a0_2 = a0 * a0;
scalar a0_3 = a0_2 * a0;
scalar a0_4 = a0_3 * a0;
scalar b0_2 = b0 * b0;
scalar b0_3 = b0_2 * b0;
scalar b0_4 = b0_3 * b0;
scalar a1_2 = a1 * a1;
scalar a1_3 = a1_2 * a1;
scalar b1_2 = b1 * b1;
scalar b1_3 = b1_2 * b1;
scalar C1 = a1 + a0;
scalar Ca = a1*C1 + a0_2;
scalar Caa = a1*Ca + a0_3;
scalar Caaa = a1*Caa + a0_4;
scalar Cb = b1*(b1 + b0) + b0_2;
scalar Cbb = b1*Cb + b0_3;
scalar Cbbb = b1*Cbb + b0_4;
scalar Cab = 3*a1_2 + 2*a1*a0 + a0_2;
scalar Kab = a1_2 + 2*a1*a0 + 3*a0_2;
scalar Caab = a0*Cab + 4*a1_3;
scalar Kaab = a1*Kab + 4*a0_3;
scalar Cabb = 4*b1_3 + 3*b1_2*b0 + 2*b1*b0_2 + b0_3;
scalar Kabb = b1_3 + 2*b1_2*b0 + 3*b1*b0_2 + 4*b0_3;
P1 += db*C1;
Pa += db*Ca;
Paa += db*Caa;
Paaa += db*Caaa;
Pb += da*Cb;
Pbb += da*Cbb;
Pbbb += da*Cbbb;
Pab += db*(b1*Cab + b0*Kab);
Paab += db*(b1*Caab + b0*Kaab);
Pabb += da*(a1*Cabb + a0*Kabb);
}
P1 /= 2.0;
Pa /= 6.0;
Paa /= 12.0;
Paaa /= 20.0;
Pb /= -6.0;
Pbb /= -12.0;
Pbbb /= -20.0;
Pab /= 24.0;
Paab /= 60.0;
Pabb /= -60.0;
}
void Foam::compFaceIntegrals
(
const pointField& points,
const face& f,
const vector& n,
const scalar w,
const direction A,
const direction B,
const direction C,
scalar& Fa,
scalar& Fb,
scalar& Fc,
scalar& Faa,
scalar& Fbb,
scalar& Fcc,
scalar& Faaa,
scalar& Fbbb,
scalar& Fccc,
scalar& Faab,
scalar& Fbbc,
scalar& Fcca
)
{
scalar P1, Pa, Pb, Paa, Pab, Pbb, Paaa, Paab, Pabb, Pbbb;
compProjectionIntegrals
(
points,
f,
A,
B,
P1,
Pa,
Pb,
Paa,
Pab,
Pbb,
Paaa,
Paab,
Pabb,
Pbbb
);
scalar k1 = 1 / n[C];
scalar k2 = k1 * k1;
scalar k3 = k2 * k1;
scalar k4 = k3 * k1;
Fa = k1 * Pa;
Fb = k1 * Pb;
Fc = -k2 * (n[A]*Pa + n[B]*Pb + w*P1);
Faa = k1 * Paa;
Fbb = k1 * Pbb;
Fcc = k3 * (sqr(n[A])*Paa + 2*n[A]*n[B]*Pab + sqr(n[B])*Pbb
+ w*(2*(n[A]*Pa + n[B]*Pb) + w*P1));
Faaa = k1 * Paaa;
Fbbb = k1 * Pbbb;
Fccc = -k4 * (pow3(n[A])*Paaa + 3*sqr(n[A])*n[B]*Paab
+ 3*n[A]*sqr(n[B])*Pabb + pow3(n[B])*Pbbb
+ 3*w*(sqr(n[A])*Paa + 2*n[A]*n[B]*Pab + sqr(n[B])*Pbb)
+ w*w*(3*(n[A]*Pa + n[B]*Pb) + w*P1));
Faab = k1 * Paab;
Fbbc = -k2 * (n[A]*Pabb + n[B]*Pbbb + w*Pbb);
Fcca = k3 * (sqr(n[A])*Paaa + 2*n[A]*n[B]*Paab + sqr(n[B])*Pabb
+ w*(2*(n[A]*Paa + n[B]*Pab) + w*Pa));
}
void Foam::compVolumeIntegrals
(
const pointField& points,
const faceList& faces,
const cell& cFaces,
const vectorField& fNorm,
const scalarField& fW,
scalar& T0,
vector& T1,
vector& T2,
vector& TP
)
{
T0 = 0;
T1 = vector::zero;
T2 = vector::zero;
TP = vector::zero;
forAll(cFaces, i)
{
const vector& n = fNorm[i];
scalar nx = mag(n[0]);
scalar ny = mag(n[1]);
scalar nz = mag(n[2]);
direction A, B, C;
if (nx > ny && nx > nz)
{
C = 0;
}
else
{
C = (ny > nz) ? 1 : 2;
}
A = (C + 1) % 3;
B = (A + 1) % 3;
scalar Fa, Fb, Fc, Faa, Fbb, Fcc, Faaa, Fbbb, Fccc, Faab, Fbbc, Fcca;
compFaceIntegrals
(
points,
faces[cFaces[i]],
n,
fW[i],
A,
B,
C,
Fa,
Fb,
Fc,
Faa,
Fbb,
Fcc,
Faaa,
Fbbb,
Fccc,
Faab,
Fbbc,
Fcca
);
T0 += n[0] * ((A == 0) ? Fa : ((B == 0) ? Fb : Fc));
T1[A] += n[A] * Faa;
T1[B] += n[B] * Fbb;
T1[C] += n[C] * Fcc;
T2[A] += n[A] * Faaa;
T2[B] += n[B] * Fbbb;
T2[C] += n[C] * Fccc;
TP[A] += n[A] * Faab;
TP[B] += n[B] * Fbbc;
TP[C] += n[C] * Fcca;
}
T1 /= 2;
T2 /= 3;
TP /= 2;
}
// Calculate
// - r: centre of mass
// - J: inertia around origin (point 0,0,0)
void Foam::momentOfIntertia
(
const pointField& points,
const faceList& faces,
const cell& cFaces,
point& r,
tensor& J tensor& J
) )
{ {
// Face normals // Reimplemented from: Wm4PolyhedralMassProperties.cpp
vectorField fNorm(cFaces.size()); // File Version: 4.10.0 (2009/11/18)
scalarField fW(cFaces.size());
forAll(cFaces, i) // Geometric Tools, LC
// Copyright (c) 1998-2010
// Distributed under the Boost Software License, Version 1.0.
// http://www.boost.org/LICENSE_1_0.txt
// http://www.geometrictools.com/License/Boost/LICENSE_1_0.txt
// Boost Software License - Version 1.0 - August 17th, 2003
// Permission is hereby granted, free of charge, to any person or
// organization obtaining a copy of the software and accompanying
// documentation covered by this license (the "Software") to use,
// reproduce, display, distribute, execute, and transmit the
// Software, and to prepare derivative works of the Software, and
// to permit third-parties to whom the Software is furnished to do
// so, all subject to the following:
// The copyright notices in the Software and this entire
// statement, including the above license grant, this restriction
// and the following disclaimer, must be included in all copies of
// the Software, in whole or in part, and all derivative works of
// the Software, unless such copies or derivative works are solely
// in the form of machine-executable object code generated by a
// source language processor.
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
// OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, TITLE AND
// NON-INFRINGEMENT. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR
// ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE FOR ANY DAMAGES OR
// OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
// USE OR OTHER DEALINGS IN THE SOFTWARE.
const scalar r6 = 1.0/6.0;
const scalar r24 = 1.0/24.0;
const scalar r60 = 1.0/60.0;
const scalar r120 = 1.0/120.0;
// order: 1, x, y, z, x^2, y^2, z^2, xy, yz, zx
scalarField integrals(10, 0.0);
forAll(triFaces, i)
{ {
label faceI = cFaces[i]; const triFace& tri(triFaces[i]);
const face& f = faces[faceI]; // vertices of triangle i
vector v0 = pts[tri[0]];
vector v1 = pts[tri[1]];
vector v2 = pts[tri[2]];
fNorm[i] = f.normal(points); // cross product of edges
fNorm[i] /= mag(fNorm[i]) + VSMALL; vector eA = v1 - v0;
vector eB = v2 - v0;
vector n = eA ^ eB;
fW[i] = - (fNorm[i] & points[f[0]]); // compute integral terms
scalar tmp0, tmp1, tmp2;
scalar f1x, f2x, f3x, g0x, g1x, g2x;
tmp0 = v0.x() + v1.x();
f1x = tmp0 + v2.x();
tmp1 = v0.x()*v0.x();
tmp2 = tmp1 + v1.x()*tmp0;
f2x = tmp2 + v2.x()*f1x;
f3x = v0.x()*tmp1 + v1.x()*tmp2 + v2.x()*f2x;
g0x = f2x + v0.x()*(f1x + v0.x());
g1x = f2x + v1.x()*(f1x + v1.x());
g2x = f2x + v2.x()*(f1x + v2.x());
scalar f1y, f2y, f3y, g0y, g1y, g2y;
tmp0 = v0.y() + v1.y();
f1y = tmp0 + v2.y();
tmp1 = v0.y()*v0.y();
tmp2 = tmp1 + v1.y()*tmp0;
f2y = tmp2 + v2.y()*f1y;
f3y = v0.y()*tmp1 + v1.y()*tmp2 + v2.y()*f2y;
g0y = f2y + v0.y()*(f1y + v0.y());
g1y = f2y + v1.y()*(f1y + v1.y());
g2y = f2y + v2.y()*(f1y + v2.y());
scalar f1z, f2z, f3z, g0z, g1z, g2z;
tmp0 = v0.z() + v1.z();
f1z = tmp0 + v2.z();
tmp1 = v0.z()*v0.z();
tmp2 = tmp1 + v1.z()*tmp0;
f2z = tmp2 + v2.z()*f1z;
f3z = v0.z()*tmp1 + v1.z()*tmp2 + v2.z()*f2z;
g0z = f2z + v0.z()*(f1z + v0.z());
g1z = f2z + v1.z()*(f1z + v1.z());
g2z = f2z + v2.z()*(f1z + v2.z());
// update integrals
integrals[0] += n.x()*f1x;
integrals[1] += n.x()*f2x;
integrals[2] += n.y()*f2y;
integrals[3] += n.z()*f2z;
integrals[4] += n.x()*f3x;
integrals[5] += n.y()*f3y;
integrals[6] += n.z()*f3z;
integrals[7] += n.x()*(v0.y()*g0x + v1.y()*g1x + v2.y()*g2x);
integrals[8] += n.y()*(v0.z()*g0y + v1.z()*g1y + v2.z()*g2y);
integrals[9] += n.z()*(v0.x()*g0z + v1.x()*g1z + v2.x()*g2z);
}
integrals[0] *= r6;
integrals[1] *= r24;
integrals[2] *= r24;
integrals[3] *= r24;
integrals[4] *= r60;
integrals[5] *= r60;
integrals[6] *= r60;
integrals[7] *= r120;
integrals[8] *= r120;
integrals[9] *= r120;
// mass
mass = integrals[0];
// center of mass
cM = vector(integrals[1], integrals[2], integrals[3])/mass;
// inertia relative to origin
J.xx() = integrals[5] + integrals[6];
J.xy() = -integrals[7];
J.xz() = -integrals[9];
J.yx() = J.xy();
J.yy() = integrals[4] + integrals[6];
J.yz() = -integrals[8];
J.zx() = J.xz();
J.zy() = J.yz();
J.zz() = integrals[4] + integrals[5];
// inertia relative to center of mass
J -= mass*((cM & cM)*I - cM*cM);
// Apply density
mass *= density;
J *= density;
} }
scalar T0; void Foam::momentOfInertia::massPropertiesShell
vector T1, T2, TP;
compVolumeIntegrals
( (
points, const pointField& pts,
faces, const triFaceList& triFaces,
cFaces, scalar density,
fNorm, scalar& mass,
fW, vector& cM,
tensor& J
)
{
// Reset properties for accumulation
T0, mass = 0.0;
T1, cM = vector::zero;
T2, J = tensor::zero;
TP
// Find centre of mass
forAll(triFaces, i)
{
const triFace& tri(triFaces[i]);
triPointRef t
(
pts[tri[0]],
pts[tri[1]],
pts[tri[2]]
); );
const scalar density = 1.0; /* assume unit density */ scalar triMag = t.mag();
scalar mass = density * T0; cM += triMag*t.centre();
/* compute center of mass */ mass += triMag;
r = T1 / T0;
/* compute inertia tensor */
J.xx() = density * (T2[1] + T2[2]);
J.yy() = density * (T2[2] + T2[0]);
J.zz() = density * (T2[0] + T2[1]);
J.xy() = J.yx() = - density * TP[0];
J.yz() = J.zy() = - density * TP[1];
J.zx() = J.xz() = - density * TP[2];
///* translate inertia tensor to center of mass */
//J[XX] -= mass * (r[1]*r[1] + r[2]*r[2]);
//J[YY] -= mass * (r[2]*r[2] + r[0]*r[0]);
//J[ZZ] -= mass * (r[0]*r[0] + r[1]*r[1]);
//J[XY] = J[YX] += mass * r[0] * r[1];
//J[YZ] = J[ZY] += mass * r[1] * r[2];
//J[ZX] = J[XZ] += mass * r[2] * r[0];
} }
cM /= mass;
mass *= density;
// Find inertia around centre of mass
forAll(triFaces, i)
{
const triFace& tri(triFaces[i]);
J += triPointRef
(
pts[tri[0]],
pts[tri[1]],
pts[tri[2]]
).inertia(cM, density);
}
}
void Foam::momentOfInertia::massPropertiesSolid
(
const triSurface& surf,
scalar density,
scalar& mass,
vector& cM,
tensor& J
)
{
triFaceList faces(surf.size());
forAll(surf, i)
{
faces[i] = triFace(surf[i]);
}
massPropertiesSolid(surf.points(), faces, density, mass, cM, J);
}
void Foam::momentOfInertia::massPropertiesShell
(
const triSurface& surf,
scalar density,
scalar& mass,
vector& cM,
tensor& J
)
{
triFaceList faces(surf.size());
forAll(surf, i)
{
faces[i] = triFace(surf[i]);
}
massPropertiesShell(surf.points(), faces, density, mass, cM, J);
}
Foam::tensor Foam::momentOfInertia::applyParallelAxisTheorem
(
scalar mass,
const vector& cM,
const tensor& J,
const vector& refPt
)
{
// The displacement vector (refPt = cM) is the displacement of the
// new reference point from the centre of mass of the body that
// the inertia tensor applies to.
vector d = (refPt - cM);
return J + mass*((d & d)*I - d*d);
}
Foam::tmp<Foam::tensorField> Foam::momentOfInertia::meshInertia
(
const polyMesh& mesh
)
{
tmp<tensorField> tTf = tmp<tensorField>(new tensorField(mesh.nCells()));
tensorField& tf = tTf();
forAll(tf, cI)
{
tf[cI] = meshInertia(mesh, cI);
}
return tTf;
}
Foam::tensor Foam::momentOfInertia::meshInertia
(
const polyMesh& mesh,
label cellI
)
{
List<tetIndices> cellTets = polyMeshTetDecomposition::cellTetIndices
(
mesh,
cellI
);
triFaceList faces(cellTets.size());
forAll(cellTets, cTI)
{
faces[cTI] = cellTets[cTI].faceTriIs(mesh);
}
scalar m = 0.0;
vector cM = vector::zero;
tensor J = tensor::zero;
massPropertiesSolid(mesh.points(), faces, 1.0, m, cM, J);
return J;
}
// ************************************************************************* // // ************************************************************************* //

View File

@ -25,6 +25,9 @@ Class
momentOfInertia momentOfInertia
Description Description
Calculates the inertia tensor and principal axes and moments of a
polyhedra/cells/triSurfaces. Inertia can either be of the solid body or
of a thin shell.
SourceFiles SourceFiles
momentOfInertia.H momentOfInertia.H
@ -34,35 +37,87 @@ SourceFiles
#ifndef momentOfInertia_H #ifndef momentOfInertia_H
#define momentOfInertia_H #define momentOfInertia_H
#include "tensor.H" #include "tetPointRef.H"
#include "primitiveMesh.H" #include "triFaceList.H"
#include "triSurface.H"
#include "polyMesh.H"
#include "polyMeshTetDecomposition.H"
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
namespace Foam namespace Foam
{ {
////- Moment of inertia around cell centre for single cell. /*---------------------------------------------------------------------------*\
//tensor momentOfInertia Class momentOfInertia Declaration
//( \*---------------------------------------------------------------------------*/
// const pointField&,
// const faceList&,
// const cell&,
// const point& cc
//);
// Calculate class momentOfInertia
// - centre of mass {
// - inertia tensor around (0,0,0)
void momentOfIntertia public:
static void massPropertiesSolid
( (
const pointField&, const pointField& pts,
const faceList&, const triFaceList& triFaces,
const cell&, scalar density,
point& r, scalar& mass,
tensor& Jorigin vector& cM,
tensor& J
); );
static void massPropertiesShell
(
const pointField& pts,
const triFaceList& triFaces,
scalar density,
scalar& mass,
vector& cM,
tensor& J
);
static void massPropertiesSolid
(
const triSurface& surf,
scalar density,
scalar& mass,
vector& cM,
tensor& J
);
static void massPropertiesShell
(
const triSurface& surf,
scalar density,
scalar& mass,
vector& cM,
tensor& J
);
static tensor applyParallelAxisTheorem
(
scalar mass,
const vector& cM,
const tensor& J,
const vector& refPt
);
// Calculate the inertia tensor for all cells in the mesh
static tmp<tensorField> meshInertia
(
const polyMesh& mesh
);
// Calculate the inertia tensor the given cell
static tensor meshInertia
(
const polyMesh& mesh,
label cellI
);
};
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
} // End namespace Foam } // End namespace Foam