Test-momentOfInertia.C 6.77 KB
Newer Older
1
2
3
4
/*---------------------------------------------------------------------------*\
 =========                   |
 \\      /   F ield          | OpenFOAM: The Open Source CFD Toolbox
  \\    /    O peration      |
graham's avatar
graham committed
5
   \\  /     A nd            | Copyright (C) 2009-2011 OpenCFD Ltd.
6
7
8
9
10
    \\/      M anipulation   |
-------------------------------------------------------------------------------
License
    This file is part of OpenFOAM.

11
12
13
14
    OpenFOAM is free software: you can redistribute it and/or modify it
    under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.
15
16
17
18
19
20
21

    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
    for more details.

    You should have received a copy of the GNU General Public License
22
    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
23
24
25
26
27
28

Application
    momentOfInertiaTest

Description
    Calculates the inertia tensor and principal axes and moments of a
graham's avatar
graham committed
29
    test face, tetrahedron and cell.
30
31
32

\*---------------------------------------------------------------------------*/

33
34
35
#include "argList.H"
#include "Time.H"
#include "polyMesh.H"
36
37
#include "ListOps.H"
#include "face.H"
38
39
#include "tetPointRef.H"
#include "triFaceList.H"
40
41
#include "OFstream.H"
#include "meshTools.H"
42
#include "momentOfInertia.H"
43
44
45
46
47

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

using namespace Foam;

48
int main(int argc, char *argv[])
49
{
50
51
52
53
54
55
    argList::addOption
    (
        "cell",
        "label",
        "cell to use for inertia calculation, defaults to 0"
    );
56

57
58
59
    #include "setRootCase.H"
    #include "createTime.H"
    #include "createPolyMesh.H"
60
61
62

    scalar density = 1.0;

63
64
    {
        label nPts = 6;
65

66
        pointField pts(nPts);
67

68
69
70
71
72
73
        pts[0] = point(4.495, 3.717, -4.112);
        pts[1] = point(4.421, 3.932, -4.112);
        pts[2] = point(4.379, 4.053, -4.112);
        pts[3] = point(4.301, 4.026, -4.300);
        pts[4] = point(4.294, 4.024, -4.317);
        pts[5] = point(4.409, 3.687, -4.317);
74

75
        face f(identity(nPts));
76

77
        point Cf = f.centre(pts);
78

79
        tensor J = tensor::zero;
80

81
        J = f.inertia(pts, Cf, density);
82

83
        vector eVal = eigenValues(J);
84

85
        tensor eVec = eigenVectors(J);
86

87
88
89
90
        Info<< nl << "Inertia tensor of test face " << J << nl
            << "eigenValues (principal moments) " << eVal << nl
            << "eigenVectors (principal axes) " << eVec
            << endl;
91

92
        OFstream str("momentOfInertiaTestFace.obj");
93

94
95
96
97
98
99
100
101
102
        Info<< nl << "Writing test face and scaled principal axes to "
            << str.name() << endl;

        forAll(pts, ptI)
        {
            meshTools::writeOBJ(str, pts[ptI]);
        }

        str << "l";
103

104
105
106
107
        forAll(f, fI)
        {
            str << ' ' << fI + 1;
        }
108

109
        str << " 1" << endl;
110

111
112
113
114
115
116
117
118
119
120
121
122
        scalar scale = mag(Cf - pts[f[0]])/eVal.component(findMin(eVal));

        meshTools::writeOBJ(str, Cf);
        meshTools::writeOBJ(str, Cf + scale*eVal.x()*eVec.x());
        meshTools::writeOBJ(str, Cf + scale*eVal.y()*eVec.y());
        meshTools::writeOBJ(str, Cf + scale*eVal.z()*eVec.z());

        for (label i = nPts + 1; i < nPts + 4; i++)
        {
            str << "l " << nPts + 1 << ' ' << i + 1 << endl;
        }
    }
123
124

    {
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
        label nPts = 4;

        pointField pts(nPts);

        pts[0] = point(0, 0, 0);
        pts[1] = point(1, 0, 0);
        pts[2] = point(0.5, 1, 0);
        pts[3] = point(0.5, 0.5, 1);

        tetPointRef tet(pts[0], pts[1], pts[2], pts[3]);

        triFaceList tetFaces(4);

        tetFaces[0] = triFace(0, 2, 1);
        tetFaces[1] = triFace(1, 2, 3);
        tetFaces[2] = triFace(0, 3, 2);
        tetFaces[3] = triFace(0, 1, 3);

        scalar m = 0.0;
        vector cM = vector::zero;
        tensor J = tensor::zero;

147
        momentOfInertia::massPropertiesSolid(pts, tetFaces, density, m, cM, J);
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195

        vector eVal = eigenValues(J);

        tensor eVec = eigenVectors(J);

        Info<< nl
            << "Mass of tetrahedron " << m << nl
            << "Centre of mass of tetrahedron " << cM << nl
            << "Inertia tensor of tetrahedron " << J << nl
            << "eigenValues (principal moments) " << eVal << nl
            << "eigenVectors (principal axes) " << eVec
            << endl;

        OFstream str("momentOfInertiaTestTet.obj");

        Info<< nl << "Writing test tetrahedron and scaled principal axes to "
            << str.name() << endl;

        forAll(pts, ptI)
        {
            meshTools::writeOBJ(str, pts[ptI]);
        }

        forAll(tetFaces, tFI)
        {
            const triFace& f = tetFaces[tFI];

            str << "l";

            forAll(f, fI)
            {
                str << ' ' << f[fI] + 1;
            }

            str << ' ' << f[0] + 1 << endl;
        }

        scalar scale = mag(cM - pts[0])/eVal.component(findMin(eVal));

        meshTools::writeOBJ(str, cM);
        meshTools::writeOBJ(str, cM + scale*eVal.x()*eVec.x());
        meshTools::writeOBJ(str, cM + scale*eVal.y()*eVec.y());
        meshTools::writeOBJ(str, cM + scale*eVal.z()*eVec.z());

        for (label i = nPts + 1; i < nPts + 4; i++)
        {
            str << "l " << nPts + 1 << ' ' << i + 1 << endl;
        }
196
197
198
199
200
201
202
203
204
205
    }

    {
        const label cellI = args.optionLookupOrDefault("cell", 0);

        tensorField mI = momentOfInertia::meshInertia(mesh);

        tensor& J = mI[cellI];

        vector eVal = eigenValues(J);
206

207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
        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;
        }
240
241
242
243
244
245
246
247
248
    }

    Info<< nl << "End" << nl << endl;

    return 0;
}


// ************************************************************************* //