[a_cardoso]

Hi, I'm trying to simulate a 2D flow around a rectangular plate using GMSH.

I couldn't figure out how to do the boundary mesh using fields. I also tryed to subdivide and add transfinite surfaces without succes.

Using fields I got a different beahavior for vertical boundaries.

Field[1] = BoundaryLayer;
Field[1].EdgesList = {14,15,16,17};
Field[1].NodesList = {6,7,8,9};
Field[1].FanNodesList = {6,7,8,9};
Field[1].hfar = 0.05;
Field[1].hwall_n = 0.0005;
Field[1].thickness = 0.01;
Field[1].ratio = 1.1;
Field[1].AnisoMax = 1;
Field[1].Quads = 1;
Field[1].IntersectMetrics = 0;
BoundaryLayer Field = 1;

I tryed isolated fields, in addition to the strange behavior the mesh stops before the end of the face.

Field[1] = BoundaryLayer;
Field[1].EdgesList = {14,15};
Field[1].NodesList = {6,7};
Field[1].FanNodesList = {6,7};
Field[1].hfar = 0.05;
Field[1].hwall_n = 0.0005;
Field[1].thickness = 0.01;
Field[1].ratio = 1.1;
Field[1].AnisoMax = 1;
Field[1].Quads = 1;
Field[1].IntersectMetrics = 0;
BoundaryLayer Field = 1;

At last I tryed by force, using transfinite surfaces. But I got no matching meshes between the transfinite and the regular triangular meshes.

//inputs
B = 10;
H= 1;
gsmax = B/2;
gsmed = B/10;
gsmin = B/80;


hDom = 15;
lDom = 30;
l1Dom = 8;
rMed = 2;
rMax = 2;


divH = 160;
divV = 20;
nCam = 10;
camadaLimite = H/5;

tRec = Atan(H/B);
d = Sqrt(B*B+H*H);

//Printf(%f tRec);
//Printf(%f d);


a = 0.0;


//dominio
Point(1) = {0,0,0,gsmax};
Point(2) = {lDom*B,0,0,gsmax};
Point(3) = {lDom*B,hDom*B,0,gsmax};
Point(4) = {0,hDom*B,0,gsmax};
//centro
Point(5) = {l1Dom*B,hDom/2*B,0,gsmax};

//retangulo
Point(6) = {l1Dom*B+Cos(tRec+a+Pi)*d,hDom/2*B+Sin(tRec+a+Pi)*d,0,gsmin};
Point(7) = {l1Dom*B+Cos(-tRec+a)*d,hDom/2*B+Sin(-tRec+a)*d,0,gsmin};
Point(8) = {l1Dom*B+Cos(tRec+a)*d,hDom/2*B+Sin(tRec+a)*d,0,gsmin};
Point(9) = {l1Dom*B+Cos(-tRec+a+Pi)*d,hDom/2*B+Sin(-tRec+a+Pi)*d,0,gsmin};




//retangulo ref
Point(10) = {0,hDom/2*B-rMax*B,0,gsmed};
Point(11) = {lDom*B,hDom/2*B-rMax*B,0,gsmed};
Point(12) = {lDom*B,hDom/2*B+rMax*B,0,gsmed};
Point(13) = {0,hDom/2*B+rMax*B,0,gsmed};

//obstacle
Line(14) = {6,7};
Line(15) = {7,8};
Line(16) = {8,9};
Line(17) = {9,6};

//ref
Line(18) = {10,11};
Line(19) = {11,12};
Line(20) = {12,13};
Line(21) = {13,10};

//inf
Line(22) = {1,2};
Line(23) = {2,11};
Line(24) = {11,10};
Line(25) = {10,1};

//sup
Line(26) = {13,12};
Line(27) = {12,3};
Line(28) = {3,4};
Line(29) = {4,13};

Line Loop(30) = {14,15,16,17};
Line Loop(31) = {18,19,20,21};
Line Loop(32) = {22,23,24,25};
Line Loop(33) = {26,27,28,29};



//retangulo2
dc = Sqrt((B)*(B)+(H+2*camadaLimite)*(H+2*camadaLimite));
tRecC = Atan((H+2*camadaLimite)/(B));

Point(34) = {l1Dom*B+Cos(tRecC+a+Pi)*dc,hDom/2*B+Sin(tRecC+a+Pi)*dc,0,gsmin};
Point(35) = {l1Dom*B+Cos(-tRecC+a)*dc,hDom/2*B+Sin(-tRecC+a)*dc,0,gsmin};
Point(36) = {l1Dom*B+Cos(tRecC+a)*dc,hDom/2*B+Sin(tRecC+a)*dc,0,gsmin};
Point(37) = {l1Dom*B+Cos(-tRecC+a+Pi)*dc,hDom/2*B+Sin(-tRecC+a+Pi)*dc,0,gsmin};


dc = Sqrt((B+2*camadaLimite)*(B+2*camadaLimite)+(H)*(H));
tRecC = Atan((H)/(B+2*camadaLimite));

Point(38) = {l1Dom*B+Cos(tRecC+a+Pi)*dc,hDom/2*B+Sin(tRecC+a+Pi)*dc,0,gsmin};
Point(39) = {l1Dom*B+Cos(-tRecC+a)*dc,hDom/2*B+Sin(-tRecC+a)*dc,0,gsmin};
Point(40) = {l1Dom*B+Cos(tRecC+a)*dc,hDom/2*B+Sin(tRecC+a)*dc,0,gsmin};
Point(41) = {l1Dom*B+Cos(-tRecC+a+Pi)*dc,hDom/2*B+Sin(-tRecC+a+Pi)*dc,0,gsmin};


dc = Sqrt((B+2*camadaLimite)*(B+2*camadaLimite)+(H+2*camadaLimite)*(H+2*camadaLimite));
tRecC = Atan((H+2*camadaLimite)/(B+2*camadaLimite));

Point(42) = {l1Dom*B+Cos(tRecC+a+Pi)*dc,hDom/2*B+Sin(tRecC+a+Pi)*dc,0,gsmin};
Point(43) = {l1Dom*B+Cos(-tRecC+a)*dc,hDom/2*B+Sin(-tRecC+a)*dc,0,gsmin};
Point(44) = {l1Dom*B+Cos(tRecC+a)*dc,hDom/2*B+Sin(tRecC+a)*dc,0,gsmin};
Point(45) = {l1Dom*B+Cos(-tRecC+a+Pi)*dc,hDom/2*B+Sin(-tRecC+a+Pi)*dc,0,gsmin};


//1
Line(46) = {42,34};
Line(47) = {34,6};
Line(48) = {6,38};
Line(49) = {38,42};
Line Loop(50) = {46,47,48,49};

//2
Line(51) = {34,35};
Line(52) = {35,7};
Line(53) = {7,6};
Line(54) = {6,34};
Line Loop(55) = {51,52,53,54};

//3
Line(56) = {35,43};
Line(57) = {43,39};
Line(58) = {39,7};
Line(59) = {7,35};
Line Loop(60) = {56,57,58,59};

//4
Line(61) = {7,39};
Line(62) = {39,40};
Line(63) = {40,8};
Line(64) = {8,7};
Line Loop(65) = {61,62,63,64};

//5
Line(66) = {8,40};
Line(67) = {40,44};
Line(68) = {44,36};
Line(69) = {36,8};
Line Loop(70) = {66,67,68,69};

//6
Line(71) = {9,8};
Line(72) = {8,36};
Line(73) = {36,37};
Line(74) = {37,9};
Line Loop(75) = {71,72,73,74};

//7
Line(76) = {41,9};
Line(77) = {9,37};
Line(78) = {37,45};
Line(79) = {45,41};
Line Loop(80) = {76,77,78,79};


//8
Line(81) = {38,6};
Line(82) = {6,9};
Line(83) = {9,41};
Line(84) = {41,38};
Line Loop(85) = {81,82,83,84};

//externo
Line(97) = {42,43};
Line(98) = {43,44};
Line(99) = {44,45};
Line(100) = {45,42};
Line Loop(101) = {97,98,99,100};



Surface(86) = {31,101};
Surface(87) = {32};
Surface(88) = {33};

Transfinite Curve {51,53} = divH;
Transfinite Curve {52,54} = nCam;


Transfinite Curve {61,63} = nCam;
Transfinite Curve {62,64} = divV;

Transfinite Curve {71,73} = divH;
Transfinite Curve {72,74} = nCam;

Transfinite Curve {81,83} = nCam;
Transfinite Curve {82,84} = divV;


Transfinite Curve {46,48} = nCam;
Transfinite Curve {47,49} = nCam;
Transfinite Curve {56,58} = nCam;
Transfinite Curve {57,59} = nCam;
Transfinite Curve {66,68} = nCam;
Transfinite Curve {67,69} = nCam;
Transfinite Curve {76,78} = nCam;
Transfinite Curve {77,79} = nCam;

Surface(89) = {50};
Surface(90) = {55};
Surface(91) = {60};
Surface(92) = {65};
Surface(93) = {70};
Surface(94) = {75};
Surface(95) = {80};
Surface(96) = {85};

Transfinite Surface{90} = {34,35,7,6};
Transfinite Surface{92} = {7,39,40,8};
Transfinite Surface{94} = {9,8,36,37};
Transfinite Surface{96} = {38,6,9,41};

Transfinite Surface{89} = {42,34,6,38};
Transfinite Surface{91} = {35,43,39,7};
Transfinite Surface{93} = {8,40,44,36};
Transfinite Surface{95} = {41,9,37,45};

Recombine Surface{90,91,92,93,94,95,96};

Any ideas?

[edsaac]

Is there a particular reason to have a transfinite grid near the hole? If not, I'd go for changing the meshing algorithm to just get better quads (Mesh.Algorithm = 8)

(ps. check attachments (: )

[a_cardoso]

The idea is to get a regular mesh perpendicular to the surface to get better convergence, Isaw it in many foil examples.

I'll try this suggestion,

Thanks edsaak