> On 23 Apr 2015, at 23:43, ryan kim <[email protected]> wrote: > > 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. >
For general cases you can use a Field, to control the mesh depending on the distance to geometrical entities. See tutorial/t10.geo. > 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] > 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 list >> >> [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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