s=1;
Point(1) = {0,0,0,s/10};
Point(2) = {s,0,0,s/10};
Point(3) = {2*s,0,0,s/10};
Point(4) = {0,s,0,s/10};
Point(5) = {s,s,0,s/10};
Point(6) = {2*s,s,0,s/10};
Line(1) = {1,2};
Line(2) = {2,3};
Line(3) = {3,6};
Line(4) = {6,5};
Line(5) = {5,4};
Line(6) = {4,1};
Line(7) = {2,5};
Line Loop(8) = {1,7,5,6};
Plane Surface(9) = {8};
Line Loop(10) = {2,3,4,-7};
Plane Surface(11) = {10};

Physical Surface(1) = 9; 
Physical Surface(2) = 11;
Physical Line(10) = 6; // left
Physical Line(11) = 3; // right


/*********************************/
/*  Región de muestreo -  OmegaX */
/*********************************/

Point(21) = {s/4  ,s/4  ,0,s/10};
Point(22) = {s*3/4,s/4  ,0,s/10};
Point(23) = {s/4  ,s*3/4,0,s/10};
Point(24) = {s*3/4,s*3/4,0,s/10};

Line(25) = {21,22};
Line(26) = {22,24};
Line(27) = {24,23};
Line(28) = {23,21};

Line Loop(30) = {25,26,27,28};
Plane Surface(31) = {30};

Physical Surface(32) = 31;