lc = 2500.0; Point(1) = {-150000.000000,100000.000000,0.000000,lc}; Point(2) = {150000.000000,100000.000000,0.000000,lc}; Point(3) = {150000.000000,-100000.000000,0.000000,lc}; Point(4) = {-150000.000000,-100000.000000,0.000000,lc}; Point(5) = {0,0,0,lc}; Point(6) = {0,100., 0, lc}; Line(1) = {1,2}; Line(2) = {2,3}; Line(3) = {3,4}; Line(4) = {4,1}; Line(5) = {5,6}; Physical Line(101) = {1}; Physical Line(102) = {2}; Physical Line(103) = {3}; Physical Line(104) = {4}; Line Loop(105) = {1,2,3,4}; Plane Surface(106) = {105}; Physical Surface(107) = {106}; Periodic Line {1,2} = {3,4}; Field[1] = Attractor; Field[1].NNodesByEdge = 10; Field[1].EdgesList = {5}; Field[2] = Threshold; Field[2].IField = 1; Field[2].LcMin = 100.0; Field[2].LcMax = lc; Field[2].DistMin = 1000.0; Field[2].DistMax = 5000.0; Background Field = 2; Mesh.CharacteristicLengthExtendFromBoundary = 0;