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Functions | Variables
libMesh::Quality Namespace Reference

A namespace for quality utility functions. More...

Functions

std::string name (const ElemQuality q)
 This function returns a string containing some name for q.
 
std::string describe (const ElemQuality q)
 This function returns a string containing a short description of q.
 
std::vector< ElemQuality > valid (const ElemType t)
 

Variables

const unsigned int num_quals = 16
 The number of element quality types we have defined.
 

Detailed Description

A namespace for quality utility functions.

Author
John W. Peterson
Date
2002

Utility functions for computing element quality indicators.

Function Documentation

◆ describe()

std::string libMesh::Quality::describe ( const ElemQuality  q)

This function returns a string containing a short description of q.

Returns
A description for a ElemQuality enum

Useful for asking the enum what it computes.

Definition at line 146 of file elem_quality.C.

147{
148
149 std::ostringstream desc;
150
151 switch (q)
152 {
153
154 case EDGE_LENGTH_RATIO:
155 case ASPECT_RATIO:
156 desc << "Max edge length ratio\n"
157 << "at element center.\n"
158 << '\n'
159 << "Suggested ranges:\n"
160 << "Hexes: (1 -> 4)\n"
161 << "Quads: (1 -> 4)";
162 break;
163
164 case SKEW:
165 desc << "Maximum |cos A|, where A\n"
166 << "is the angle between edges\n"
167 << "at element center.\n"
168 << '\n'
169 << "Suggested ranges:\n"
170 << "Hexes: (0 -> 0.5)\n"
171 << "Quads: (0 -> 0.5)";
172 break;
173
174 case SHEAR:
175 desc << "LIBMESH_DIM / K(Js)\n"
176 << '\n'
177 << "LIBMESH_DIM = element dimension.\n"
178 << "K(Js) = Condition number of \n"
179 << " Jacobian skew matrix.\n"
180 << '\n'
181 << "Suggested ranges:\n"
182 << "Hexes(LIBMESH_DIM=3): (0.3 -> 1)\n"
183 << "Quads(LIBMESH_DIM=2): (0.3 -> 1)";
184 break;
185
186 case SHAPE:
187 desc << "LIBMESH_DIM / K(Jw)\n"
188 << '\n'
189 << "LIBMESH_DIM = element dimension.\n"
190 << "K(Jw) = Condition number of \n"
191 << " weighted Jacobian\n"
192 << " matrix.\n"
193 << '\n'
194 << "Suggested ranges:\n"
195 << "Hexes(LIBMESH_DIM=3): (0.3 -> 1)\n"
196 << "Tets(LIBMESH_DIM=3): (0.2 -> 1)\n"
197 << "Quads(LIBMESH_DIM=2): (0.3 -> 1).";
198 break;
199
200 case MAX_ANGLE:
201 desc << "Largest angle between all adjacent pairs of edges (in 2D, sides).\n"
202 << '\n'
203 << "Suggested ranges:\n"
204 << "Quads: (90 -> 135)\n"
205 << "Triangles: (60 -> 90)";
206 break;
207
208 case MIN_ANGLE:
209 desc << "Smallest angle between all adjacent pairs of edges (in 2D, sides).\n"
210 << '\n'
211 << "Suggested ranges:\n"
212 << "Quads: (45 -> 90)\n"
213 << "Triangles: (30 -> 60)";
214 break;
215
216 case MAX_DIHEDRAL_ANGLE:
217 desc << "Largest angle between all adjacent pairs of sides (in 2D, equivalent to MAX_ANGLE).\n"
218 << "In 3D, this is the largest unoriented angle between adjacent side planes, in the range [0, 90].\n"
219 << '\n'
220 << "Suggested ranges:\n"
221 << "Quads: (90 -> 135)\n"
222 << "Triangles: (60 -> 90)\n"
223 << "C0Polyhedra: (60 -> 90)";
224 break;
225
226 case MIN_DIHEDRAL_ANGLE:
227 desc << "Smallest angle between all adjacent pairs of sides (in 2D, equivalent to MIN_ANGLE).\n"
228 << "In 3D, this is the smallest unoriented angle between adjacent side planes, in the range [0, 90].\n"
229 << '\n'
230 << "Suggested ranges:\n"
231 << "Quads: (45 -> 90)\n"
232 << "Triangles: (30 -> 60)\n"
233 << "C0Polyhedra: (30 -> 90)";
234 break;
235
236 case CONDITION:
237 desc << "Condition number of the\n"
238 << "Jacobian matrix.\n"
239 << '\n'
240 << "Suggested ranges:\n"
241 << "Quads: (1 -> 4)\n"
242 << "Hexes: (1 -> 8)\n"
243 << "Tris: (1 -> 1.3)\n"
244 << "Tets: (1 -> 3)";
245 break;
246
247 case DISTORTION:
248 desc << "min |J| * A / <A>\n"
249 << '\n'
250 << "|J| = norm of Jacobian matrix\n"
251 << " A = actual area\n"
252 << "<A> = reference area\n"
253 << '\n'
254 << "Suggested ranges:\n"
255 << "Quads: (0.6 -> 1), <A>=4\n"
256 << "Hexes: (0.6 -> 1), <A>=8\n"
257 << "Tris: (0.6 -> 1), <A>=1/2\n"
258 << "Tets: (0.6 -> 1), <A>=1/6";
259 break;
260
261 case TAPER:
262 desc << "Maximum ratio of lengths\n"
263 << "derived from opposite edges.\n"
264 << '\n'
265 << "Suggested ranges:\n"
266 << "Quads: (0.7 -> 1)\n"
267 << "Hexes: (0.4 -> 1)";
268 break;
269
270 case WARP:
271 desc << "cos D\n"
272 << '\n'
273 << "D = minimum dihedral angle\n"
274 << " formed by diagonals.\n"
275 << '\n'
276 << "Suggested ranges:\n"
277 << "Quads: (0.9 -> 1)";
278 break;
279
280 case STRETCH:
281 desc << "Sqrt(3) * L_min / L_max\n"
282 << '\n'
283 << "L_min = minimum edge length.\n"
284 << "L_max = maximum edge length.\n"
285 << '\n'
286 << "Suggested ranges:\n"
287 << "Quads: (0.25 -> 1)\n"
288 << "Hexes: (0.25 -> 1)";
289 break;
290
291 case DIAGONAL:
292 desc << "D_min / D_max\n"
293 << '\n'
294 << "D_min = minimum diagonal.\n"
295 << "D_max = maximum diagonal.\n"
296 << '\n'
297 << "Suggested ranges:\n"
298 << "Hexes: (0.65 -> 1)";
299 break;
300
301 case ASPECT_RATIO_BETA:
302 desc << "CR / (3 * IR)\n"
303 << '\n'
304 << "CR = circumsphere radius\n"
305 << "IR = inscribed sphere radius\n"
306 << '\n'
307 << "Suggested ranges:\n"
308 << "Tets: (1 -> 3)";
309 break;
310
311 case ASPECT_RATIO_GAMMA:
312 desc << "S^(3/2) / 8.479670 * V\n"
313 << '\n'
314 << "S = sum(si*si/6)\n"
315 << "si = edge length\n"
316 << "V = volume\n"
317 << '\n'
318 << "Suggested ranges:\n"
319 << "Tets: (1 -> 3)";
320 break;
321
322 case SIZE:
323 desc << "min (|J|, |1/J|)\n"
324 << '\n'
325 << "|J| = norm of Jacobian matrix.\n"
326 << '\n'
327 << "Suggested ranges:\n"
328 << "Quads: (0.3 -> 1)\n"
329 << "Hexes: (0.5 -> 1)\n"
330 << "Tris: (0.25 -> 1)\n"
331 << "Tets: (0.2 -> 1)";
332 break;
333
334 case JACOBIAN:
335 case SCALED_JACOBIAN:
336 desc << "Minimum nodal Jacobian.\n"
337 << "The nodal Jacobians are computed by taking the cross product (2D) or scalar product (3D) of the adjacent edges that meet at that node.\n"
338 << "In the SCALED_JACOBIAN case, we also then divide by the lengths of each of the associated edges.\n"
339 << "For Pyramid elements where four edges meet at the apex node, special handling is required.\n"
340 << '\n'
341 << "Suggested acceptable ranges (from Cubit documentation) for SCALED_JACOBIAN metric:\n"
342 << "Quads/Hexes: (0.5 -> 1)\n"
343 << "Tris/Tets: (0.2 -> 1.0)";
344 break;
345
346 default:
347 desc << "Unknown";
348 break;
349 }
350
351 return desc.str();
352}

References libMesh::ASPECT_RATIO, libMesh::ASPECT_RATIO_BETA, libMesh::ASPECT_RATIO_GAMMA, libMesh::CONDITION, libMesh::DIAGONAL, libMesh::DISTORTION, libMesh::EDGE_LENGTH_RATIO, libMesh::JACOBIAN, libMesh::MAX_ANGLE, libMesh::MAX_DIHEDRAL_ANGLE, libMesh::MIN_ANGLE, libMesh::MIN_DIHEDRAL_ANGLE, libMesh::SCALED_JACOBIAN, libMesh::SHAPE, libMesh::SHEAR, libMesh::SIZE, libMesh::SKEW, libMesh::STRETCH, libMesh::TAPER, and libMesh::WARP.

◆ name()

std::string libMesh::Quality::name ( const ElemQuality  q)

This function returns a string containing some name for q.

Returns
A descriptive name for a ElemQuality enum

Useful for asking the enum what its name is. I added this since you may want a simple way to attach a name or description to the ElemQuality enums. It can be removed if it is found to be useless.

Definition at line 42 of file elem_quality.C.

43{
44 std::string its_name;
45
46 switch (q)
47 {
48
49 case EDGE_LENGTH_RATIO:
50 its_name = "Edge Length Ratio";
51 break;
52
53 case ASPECT_RATIO:
54 its_name = "Aspect Ratio";
55 break;
56
57 case SKEW:
58 its_name = "Skew";
59 break;
60
61 case SHEAR:
62 its_name = "Shear";
63 break;
64
65 case SHAPE:
66 its_name = "Shape";
67 break;
68
69 case MAX_ANGLE:
70 its_name = "Maximum Angle";
71 break;
72
73 case MIN_ANGLE:
74 its_name = "Minimum Angle";
75 break;
76
77 case MAX_DIHEDRAL_ANGLE:
78 its_name = "Maximum Dihedral Angle";
79 break;
80
81 case MIN_DIHEDRAL_ANGLE:
82 its_name = "Minimum Dihedral Angle";
83 break;
84
85 case CONDITION:
86 its_name = "Condition Number";
87 break;
88
89 case DISTORTION:
90 its_name = "Distortion";
91 break;
92
93 case TAPER:
94 its_name = "Taper";
95 break;
96
97 case WARP:
98 its_name = "Warp";
99 break;
100
101 case STRETCH:
102 its_name = "Stretch";
103 break;
104
105 case DIAGONAL:
106 its_name = "Diagonal";
107 break;
108
109 case ASPECT_RATIO_BETA:
110 its_name = "AR Beta";
111 break;
112
113 case ASPECT_RATIO_GAMMA:
114 its_name = "AR Gamma";
115 break;
116
117 case SIZE:
118 its_name = "Size";
119 break;
120
121 case JACOBIAN:
122 its_name = "Jacobian";
123 break;
124
125 case SCALED_JACOBIAN:
126 its_name = "Scaled Jacobian";
127 break;
128
129 default:
130 its_name = "Unknown";
131 break;
132 }
133
134 return its_name;
135}

References libMesh::ASPECT_RATIO, libMesh::ASPECT_RATIO_BETA, libMesh::ASPECT_RATIO_GAMMA, libMesh::CONDITION, libMesh::DIAGONAL, libMesh::DISTORTION, libMesh::EDGE_LENGTH_RATIO, libMesh::JACOBIAN, libMesh::MAX_ANGLE, libMesh::MAX_DIHEDRAL_ANGLE, libMesh::MIN_ANGLE, libMesh::MIN_DIHEDRAL_ANGLE, libMesh::SCALED_JACOBIAN, libMesh::SHAPE, libMesh::SHEAR, libMesh::SIZE, libMesh::SKEW, libMesh::STRETCH, libMesh::TAPER, and libMesh::WARP.

Referenced by main(), and ElemTest< elem_type >::test_quality().

◆ valid()

std::vector< ElemQuality > libMesh::Quality::valid ( const ElemType  t)
Returns
The "valid" ElemQuality metrics for a given ElemType element type. Valid metrics are those which have Elem::qual_bounds() defined. Not all "valid" metrics are actually implemented in the code.

Definition at line 355 of file elem_quality.C.

356{
357 std::vector<ElemQuality> v;
358
359 switch (t)
360 {
361 case EDGE2:
362 case EDGE3:
363 case EDGE4:
364 {
365 // None yet
366 break;
367 }
368
369 case TRI3:
370 case TRISHELL3:
371 case TRI6:
372 case TRI7:
373 {
374 v = {
375 CONDITION,
376 DISTORTION,
377 EDGE_LENGTH_RATIO,
378 JACOBIAN,
379 SCALED_JACOBIAN,
380 MAX_ANGLE,
381 MIN_ANGLE,
382 MAX_DIHEDRAL_ANGLE,
383 MIN_DIHEDRAL_ANGLE,
384 SHAPE,
385 SIZE
386 };
387
388 break;
389 }
390
391 case QUAD4:
392 case QUADSHELL4:
393 case QUAD8:
394 case QUADSHELL8:
395 case QUAD9:
396 case QUADSHELL9:
397 {
398 v = {
399 ASPECT_RATIO,
400 CONDITION,
401 DISTORTION,
402 EDGE_LENGTH_RATIO,
403 JACOBIAN,
404 SCALED_JACOBIAN,
405 MAX_ANGLE,
406 MIN_ANGLE,
407 MAX_DIHEDRAL_ANGLE,
408 MIN_DIHEDRAL_ANGLE,
409 SHAPE,
410 SHEAR,
411 SIZE,
412 SKEW,
413 STRETCH,
414 TAPER,
415 WARP
416 };
417
418 break;
419 }
420
421 case TET4:
422 case TET10:
423 case TET14:
424 {
425 v = {
426 ASPECT_RATIO_BETA,
427 ASPECT_RATIO_GAMMA,
428 CONDITION,
429 DISTORTION,
430 JACOBIAN,
431 SCALED_JACOBIAN,
432 MAX_ANGLE,
433 MIN_ANGLE,
434 MAX_DIHEDRAL_ANGLE,
435 MIN_DIHEDRAL_ANGLE,
436 SHAPE,
437 SIZE
438 };
439
440 break;
441 }
442
443 case HEX8:
444 case HEX20:
445 case HEX27:
446 {
447 v = {
448 ASPECT_RATIO,
449 CONDITION,
450 DIAGONAL,
451 DISTORTION,
452 JACOBIAN,
453 SCALED_JACOBIAN,
454 MAX_ANGLE,
455 MIN_ANGLE,
456 MAX_DIHEDRAL_ANGLE,
457 MIN_DIHEDRAL_ANGLE,
458 SHAPE,
459 SHEAR,
460 SIZE,
461 SKEW,
462 STRETCH,
463 TAPER
464 };
465
466 break;
467 }
468
469 case PRISM6:
470 case PRISM18:
471 case PRISM20:
472 case PRISM21:
473 {
474 v = {
475 EDGE_LENGTH_RATIO,
476 MAX_ANGLE,
477 MIN_ANGLE,
478 MAX_DIHEDRAL_ANGLE,
479 MIN_DIHEDRAL_ANGLE,
480 };
481
482 break;
483 }
484
485 case PYRAMID5:
486 case PYRAMID13:
487 case PYRAMID14:
488 case PYRAMID18:
489 {
490 v = {
491 EDGE_LENGTH_RATIO,
492 MAX_ANGLE,
493 MIN_ANGLE,
494 MAX_DIHEDRAL_ANGLE,
495 MIN_DIHEDRAL_ANGLE,
496 };
497
498 break;
499 }
500
501 case C0POLYGON:
502 {
503 v = {
504 EDGE_LENGTH_RATIO,
505 JACOBIAN,
506 SCALED_JACOBIAN,
507 MAX_ANGLE,
508 MIN_ANGLE
509 };
510
511 break;
512 }
513
514 case C0POLYHEDRON:
515 {
516 // The generic Jacobian metrics only inspect vertices with
517 // exactly three adjacent edges, but arbitrary polyhedra may
518 // have vertices of higher valence.
519 v = {
520 EDGE_LENGTH_RATIO,
521 MAX_ANGLE,
522 MIN_ANGLE,
523 MAX_DIHEDRAL_ANGLE,
524 MIN_DIHEDRAL_ANGLE
525 };
526
527 break;
528 }
529
530#ifdef LIBMESH_ENABLE_INFINITE_ELEMENTS
531
532 case INFEDGE2:
533 {
534 // None yet
535 break;
536 }
537
538 case INFQUAD4:
539 case INFQUAD6:
540 case INFHEX8:
541 case INFHEX16:
542 case INFHEX18:
543 case INFPRISM6:
544 case INFPRISM12:
545 {
546 v = {
547 MAX_ANGLE,
548 MIN_ANGLE,
549 MAX_DIHEDRAL_ANGLE,
550 MIN_DIHEDRAL_ANGLE,
551 };
552
553 break;
554 }
555
556#endif
557
558
559 default:
560 libmesh_error_msg("Undefined element type!");
561 }
562
563 return v;
564}

References libMesh::ASPECT_RATIO, libMesh::ASPECT_RATIO_BETA, libMesh::ASPECT_RATIO_GAMMA, libMesh::C0POLYGON, libMesh::C0POLYHEDRON, libMesh::CONDITION, libMesh::DIAGONAL, libMesh::DISTORTION, libMesh::EDGE2, libMesh::EDGE3, libMesh::EDGE4, libMesh::EDGE_LENGTH_RATIO, libMesh::HEX20, libMesh::HEX27, libMesh::HEX8, libMesh::INFEDGE2, libMesh::INFHEX16, libMesh::INFHEX18, libMesh::INFHEX8, libMesh::INFPRISM12, libMesh::INFPRISM6, libMesh::INFQUAD4, libMesh::INFQUAD6, libMesh::JACOBIAN, libMesh::MAX_ANGLE, libMesh::MAX_DIHEDRAL_ANGLE, libMesh::MIN_ANGLE, libMesh::MIN_DIHEDRAL_ANGLE, libMesh::PRISM18, libMesh::PRISM20, libMesh::PRISM21, libMesh::PRISM6, libMesh::PYRAMID13, libMesh::PYRAMID14, libMesh::PYRAMID18, libMesh::PYRAMID5, libMesh::QUAD4, libMesh::QUAD8, libMesh::QUAD9, libMesh::QUADSHELL4, libMesh::QUADSHELL8, libMesh::QUADSHELL9, libMesh::SCALED_JACOBIAN, libMesh::SHAPE, libMesh::SHEAR, libMesh::SIZE, libMesh::SKEW, libMesh::STRETCH, libMesh::TAPER, libMesh::TET10, libMesh::TET14, libMesh::TET4, libMesh::TRI3, libMesh::TRI6, libMesh::TRI7, libMesh::TRISHELL3, and libMesh::WARP.

Referenced by ElemTest< elem_type >::test_quality().

Variable Documentation

◆ num_quals

const unsigned int libMesh::Quality::num_quals = 16

The number of element quality types we have defined.

This needs to be updated if you add one.

Definition at line 48 of file elem_quality.h.

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