Hi German and gmsh team, Thanks for the discussion. This manual point adding can play the trick for this problem but it is "*not a systematic"* way to apply. For a general irregular geometry, to automatically add this point or even a number of points in the empty area is a problem! I expect gmsh has the feature to make this fine to coarse transition. However, I dig deep into gmsh literature and did not find *this feature to have fine mesh ONLY around the small geometry*.
I hope gmsh team can confirm this with me, or advise someway to achieve this other than the trick to insert point in empty area manually. Thanks, Kim 2015-04-23 4:12 GMT-07:00 Theler German Guillermo <[email protected]>: > These three lines at the end of your geo file will do the trick: > > Plane Surface(22) = {1, 2, 3, 4, 5}; > Point(23) = {0, 0, 0, lc}; > Point {23} In Surface {22}; > > > -- > *Germán Theler :: **CTO Eng & IT* > > *CITES* – Centro de Innovación Tecnológica Empresarial y Social S.A. > Dirección General Sancor Seguros > Grupo Sancor Seguros > tel +54 3493 –428 500 – Int.:* 3374* > [email protected] <[email protected]> > *www.cites-gss.com <http://www.cites-gss.com>* - > www.gruposancorseguros.com > > > > On Wed, 2015-04-22 at 01:38 -0700, ryan kim wrote: > > I have used gmsh in my application for a while. However, one kind of > simple and standard geometry still makes bad mesh result. The geometry is > just a rectangular plane with four small holes at each corner like this: > ------------------------------------- > | | > | | > | __ __ | > | | | | | | > | --- ---- | > | | > | | > | __ __ | > | | | | | | > | ---- ---- | > | | > | | > |____________________ | > > > Surprisingly, gmsh generated fine mesh not only around the four holes, > but also in the area between the holes. Therefore, the entire mesh size is > huge. The ideal mesh should only have fine mesh around the holes at corner > since coarse mesh is enough for the center area. > > > I read the history of the mailing list and find some discussion about > this problem. However, no good solution has been provided. Someone > suggested using > Mesh.CharacteristicLengthExtendFromBoundary= 0; > > However, it indeed generated coarse mesh at the center but the triangle > quality is bad with very sharp angle. > > Using fields: "Attractor", and "Threshold" as in tutorial t10 does not > work as well. > > > > Here is the script of the simple test case as described above. I also > attached the bad mesh result as I mentioned. Hope someone can discuss this > classic problem with me. > > lc = 10; > lc1 = 1; > Point(1) = {-100, -100, 0, lc}; > Point(2) = {100, -100, 0, lc} ; > Point(3) = {100, 100, 0, lc} ; > Point(4) = {-100, 100, 0, lc} ; > Line(1) = {1,2} ; > Line(2) = {3,2} ; > Line(3) = {3,4} ; > Line(4) = {4,1} ; > Line Loop(1) = {4,1,-2,3}; > > Point(5) = {49, 49, 0, lc1}; > Point(6) = {49, 51, 0, lc1} ; > Point(7) = {51, 51, 0, lc1} ; > Point(8) = {51, 49, 0, lc1} ; > Line(6) = {5,6} ; > Line(7) = {7,6} ; > Line(8) = {7,8} ; > Line(9) = {8,5} ; > Line Loop(2) = {9,6,-7,8}; > > Point(11) = {49, -49, 0, lc1}; > Point(12) = {49, -51, 0, lc1}; > Point(13) = {51, -51, 0, lc1}; > Point(14) = {51, -49, 0, lc1}; > Line(10) = {11,12} ; > Line(11) = {13,12} ; > Line(12) = {13,14} ; > Line(13) = {14,11} ; > Line Loop(3) = {13,10,-11,12}; > > Point(15) = {-49, 49, 0, lc1}; > Point(16) = {-49, 51, 0, lc1} ; > Point(17) = {-51, 51, 0, lc1} ; > Point(18) = {-51, 49, 0, lc1} ; > Line(14) = {15,16} ; > Line(15) = {17,16} ; > Line(16) = {17,18} ; > Line(17) = {18,15} ; > Line Loop(4) = {17,14,-15,16}; > > Point(19) = {-49, -49, 0, lc1}; > Point(20) = {-49, -51, 0, lc1} ; > Point(21) = {-51, -51, 0, lc1} ; > Point(22) = {-51, -49, 0, lc1} ; > Line(18) = {19,20} ; > Line(19) = {21,20} ; > Line(20) = {21,22} ; > Line(21) = {22,19} ; > Line Loop(5) = {21,18,-19,20}; > > Plane Surface(1) = {1, 2, 3, 4, 5} ; > //Mesh.CharacteristicLengthExtendFromBoundary= 0; > > > > Thanks, > > Kim > > > > > _______________________________________________ > gmsh mailing [email protected]http://www.geuz.org/mailman/listinfo/gmsh > > ------------------------------ > Imprima este mensaje *sólo si es absolutamente necesario*. > Para imprimir, en lo posible utilice el papel de ambos lados. > El Grupo Sancor Seguros se compromete con el cuidado del medioambiente. > > > ************AVISO DE CONFIDENCIALIDAD************ > > El Grupo Sancor Seguros comunica que: > > Este mensaje y todos los archivos adjuntos a el son para uso exclusivo del > destinatario y pueden contener información confidencial o propietaria, cuya > divulgación es sancionada por ley. 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