[dsn]

Hello Everyone,

I am trying to generate a c-grid for an airfoil by dividing it into blocks in gmsh. As shown below, the region ahead of the airfoil does not yield structured grid as I want. Can someone please tell me why this is happening. I have attached the .geo file too.

I have spent a lot of time on this and still dont seem to understand why this is happening.

mesh_size= 0;
Point(1)= {0,6e-06,0,mesh_size};
Point(2)= {0.000685,0.006377,0,mesh_size};
Point(3)= {0.002737,0.012991,0,mesh_size};
Point(4)= {0.006152,0.019846,0,mesh_size};
Point(5)= {0.010919,0.026942,0,mesh_size};
Point(6)= {0.017025,0.034234,0,mesh_size};
Point(7)= {0.024455,0.041616,0,mesh_size};
Point(8)= {0.033187,0.048946,0,mesh_size};
Point(9)= {0.043198,0.056081,0,mesh_size};
Point(10)= {0.054459,0.062883,0,mesh_size};
Point(11)= {0.066941,0.069232,0,mesh_size};
Point(12)= {0.080609,0.075022,0,mesh_size};
Point(13)= {0.095426,0.080171,0,mesh_size};
Point(14)= {0.111351,0.084627,0,mesh_size};
Point(15)= {0.12834,0.088368,0,mesh_size};
Point(16)= {0.146346,0.091398,0,mesh_size};
Point(17)= {0.165321,0.093747,0,mesh_size};
Point(18)= {0.185213,0.095466,0,mesh_size};
Point(19)= {0.205966,0.096609,0,mesh_size};
Point(20)= {0.227524,0.097229,0,mesh_size};
Point(21)= {0.249829,0.097363,0,mesh_size};
Point(22)= {0.272818,0.097041,0,mesh_size};
Point(23)= {0.296428,0.096292,0,mesh_size};
Point(24)= {0.320596,0.095146,0,mesh_size};
Point(25)= {0.345255,0.093641,0,mesh_size};
Point(26)= {0.370336,0.09181,0,mesh_size};
Point(27)= {0.395773,0.089686,0,mesh_size};
Point(28)= {0.421494,0.087293,0,mesh_size};
Point(29)= {0.447429,0.084649,0,mesh_size};
Point(30)= {0.473507,0.081766,0,mesh_size};
Point(31)= {0.499657,0.078653,0,mesh_size};
Point(32)= {0.525807,0.075319,0,mesh_size};
Point(33)= {0.551886,0.071774,0,mesh_size};
Point(34)= {0.577821,0.068036,0,mesh_size};
Point(35)= {0.603542,0.064132,0,mesh_size};
Point(36)= {0.628978,0.060102,0,mesh_size};
Point(37)= {0.65406,0.055992,0,mesh_size};
Point(38)= {0.678718,0.051837,0,mesh_size};
Point(39)= {0.702886,0.047661,0,mesh_size};
Point(40)= {0.726497,0.043482,0,mesh_size};
Point(41)= {0.749486,0.039319,0,mesh_size};
Point(42)= {0.77179,0.035192,0,mesh_size};
Point(43)= {0.793348,0.031121,0,mesh_size};
Point(44)= {0.814102,0.027125,0,mesh_size};
Point(45)= {0.833993,0.023224,0,mesh_size};
Point(46)= {0.852968,0.01944,0,mesh_size};
Point(47)= {0.870975,0.015791,0,mesh_size};
Point(48)= {0.887964,0.012299,0,mesh_size};
Point(49)= {0.903888,0.008982,0,mesh_size};
Point(50)= {0.918705,0.00586,0,mesh_size};
Point(51)= {0.932373,0.00295,0,mesh_size};
Point(52)= {0.944855,0.000268,0,mesh_size};
Point(53)= {0.956117,-0.002173,0,mesh_size};
Point(54)= {0.966128,-0.004358,0,mesh_size};
Point(55)= {0.97486,-0.006275,0,mesh_size};
Point(56)= {0.982289,-0.007913,0,mesh_size};
Point(57)= {0.988396,-0.009264,0,mesh_size};
Point(58)= {0.993163,-0.010321,0,mesh_size};
Point(59)= {0.996577,-0.011079,0,mesh_size};
Point(60)= {0.998972,-0.011611,0,mesh_size};
Point(61)= {1,-0.01184,0,mesh_size};
Point(62)= {0,6e-06,0,mesh_size};
Point(63)= {0.000685,-0.006083,0,mesh_size};
Point(64)= {0.002737,-0.011828,0,mesh_size};
Point(65)= {0.006152,-0.017176,0,mesh_size};
Point(66)= {0.010919,-0.022102,0,mesh_size};
Point(67)= {0.017025,-0.026594,0,mesh_size};
Point(68)= {0.024455,-0.030647,0,mesh_size};
Point(69)= {0.033187,-0.034265,0,mesh_size};
Point(70)= {0.043198,-0.037466,0,mesh_size};
Point(71)= {0.054459,-0.040292,0,mesh_size};
Point(72)= {0.066941,-0.0428,0,mesh_size};
Point(73)= {0.080609,-0.045058,0,mesh_size};
Point(74)= {0.095426,-0.047127,0,mesh_size};
Point(75)= {0.111351,-0.049056,0,mesh_size};
Point(76)= {0.12834,-0.050877,0,mesh_size};
Point(77)= {0.146346,-0.052611,0,mesh_size};
Point(78)= {0.165321,-0.054285,0,mesh_size};
Point(79)= {0.185213,-0.055918,0,mesh_size};
Point(80)= {0.205966,-0.057509,0,mesh_size};
Point(81)= {0.227524,-0.059027,0,mesh_size};
Point(82)= {0.249829,-0.060432,0,mesh_size};
Point(83)= {0.272818,-0.061688,0,mesh_size};
Point(84)= {0.296428,-0.062761,0,mesh_size};
Point(85)= {0.320596,-0.063603,0,mesh_size};
Point(86)= {0.345255,-0.064174,0,mesh_size};
Point(87)= {0.370336,-0.064456,0,mesh_size};
Point(88)= {0.395773,-0.064447,0,mesh_size};
Point(89)= {0.421494,-0.064155,0,mesh_size};
Point(90)= {0.447429,-0.063592,0,mesh_size};
Point(91)= {0.473507,-0.062763,0,mesh_size};
Point(92)= {0.499657,-0.061674,0,mesh_size};
Point(93)= {0.525807,-0.060333,0,mesh_size};
Point(94)= {0.551886,-0.058758,0,mesh_size};
Point(95)= {0.577821,-0.056977,0,mesh_size};
Point(96)= {0.603542,-0.05503,0,mesh_size};
Point(97)= {0.628978,-0.05296,0,mesh_size};
Point(98)= {0.65406,-0.050797,0,mesh_size};
Point(99)= {0.678718,-0.048564,0,mesh_size};
Point(100)= {0.702886,-0.046275,0,mesh_size};
Point(101)= {0.726497,-0.043945,0,mesh_size};
Point(102)= {0.749486,-0.041591,0,mesh_size};
Point(103)= {0.77179,-0.039228,0,mesh_size};
Point(104)= {0.793348,-0.036873,0,mesh_size};
Point(105)= {0.814102,-0.03454,0,mesh_size};
Point(106)= {0.833993,-0.032247,0,mesh_size};
Point(107)= {0.852968,-0.030012,0,mesh_size};
Point(108)= {0.870975,-0.027852,0,mesh_size};
Point(109)= {0.887964,-0.025793,0,mesh_size};
Point(110)= {0.903888,-0.023849,0,mesh_size};
Point(111)= {0.918705,-0.022033,0,mesh_size};
Point(112)= {0.932373,-0.02035,0,mesh_size};
Point(113)= {0.944855,-0.018805,0,mesh_size};
Point(114)= {0.956117,-0.0174,0,mesh_size};
Point(115)= {0.966128,-0.016143,0,mesh_size};
Point(116)= {0.97486,-0.015039,0,mesh_size};
Point(117)= {0.982289,-0.014096,0,mesh_size};
Point(118)= {0.988396,-0.01332,0,mesh_size};
Point(119)= {0.993163,-0.012713,0,mesh_size};
Point(120)= {0.996577,-0.012277,0,mesh_size};
Point(121)= {0.998972,-0.011972,0,mesh_size};
Point(122)= {1,-0.01184,0,mesh_size};

Spline(1) = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20};
Spline(2) = {1, 63, 64, 65, 66, 67, 68,69,70,71,72,73,74,75,76,77,78,79,80,81};

Spline(3) = {20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61};

Spline(4) = {61, 121, 120, 119, 118, 117, 116, 115, 114, 113, 112, 111, 110, 109, 108, 107, 106, 105, 104, 103, 102, 101, 100, 99, 98, 97, 96, 95, 94, 93, 92, 91, 90, 89, 88, 87, 86, 85, 84, 83, 82, 81};



Point(123) = {1, 2.01184, 0, mesh_size};
Point(124) = {1, -1.98816, 0, mesh_size};
Point(125) = {2, -1.98816, 0, mesh_size};
Point(126) = {2, 2.01184, 0, mesh_size};
Point(127) = {2,6e-06,0,mesh_size};
Point(128) = {1,-0.01184,0,mesh_size};
//Point(129) = {-15,6e-06,0,mesh_size};
Point(130) = {0.227524,2.01184,0,mesh_size};
Point(131) = {0.227524,-1.98816,0,mesh_size};
Point(132) = {-2,2.01184,0,mesh_size};
Point(133) = {-2,-1.98816,0,mesh_size};
//Point(134) = {-2,6e-06,0,mesh_size};


Line(6) = {131, 124};
Line(7) = {124, 125};
Line(8) = {125, 127};
Line(9) = {127, 126};
Line(10) = {126, 123};
Line(11) = {123, 130};
Line(14) = {127, 61};
Line(15) = {61, 123};
Line(16) = {61, 124};
Line(17) = {130, 20};
Line(18) = {81, 131};
Line(34) = {132, 133};
Line(36) = {133, 131};
Line(37) = {132, 130};


Line Loop(24) = {17, 3, 15, 11};
Plane Surface(25) = {24};
Line Loop(26) = {10, -15, -14, 9};
Plane Surface(27) = {26};
Line Loop(28) = {8, 14, 16, 7};
Plane Surface(29) = {28};
Line Loop(30) = {16, -6, -18, -4};
Plane Surface(31) = {30};
Line Loop(38) = {17, -1, 2, 18, -36, -34, 37};
Plane Surface(39) = {38};

Transfinite Line {9,15,17} = 10;
Transfinite Line {8,16,18} = 10;
Transfinite Surface "*";
Recombine Surface "*";