[chrris33]

I am trying to create a mesh to do 2-D testing on an airfoil using OpenFOAM. While I am understanding the process of creating the mesh, I am very confused on how gmsh defines the size of the mesh. I have a couple of questions.

Is there a way for me to control the amount of cells in an unstructured mesh?

When I run gmshToFoam, why am I still getting undefined faces? I thought I have defined all of mine.

I am very new to all of this and would love your help.

Here is my gmsh .geo file data:

// Boundary Points
Point(1) = {0, 0, 0, 1};
Point(2) = {-150, 0, 0, 1};
Point(3) = {0, 150, 0, 1};
Point(4) = {225, 150, 0, 1};
Point(5) = {225, -150, 0, 1};
Point(6) = {0, -150, 0, 1};
Point(7) = {225, 0, 0, 1};

// Airfoil Points
Point(8) = {-3.75,0,0,1};
Point(9) = {.755,0.900,0,1};
Point(10) = {11.25,0.019,0,1};
Point(11) = {11.25, 0, 0, 1};
Point(12) = {11.25, -.019,0,1};
Point(13) = {.755,-.900,0,1};
Point(14) = {-2.523,.651,0,1};
Point(15) = {7.71,.45,0,1};
Point(16) = {7.71,-.45,0,1};
Point(17) = {-2.523,-.651,0,1};




// Boundary Lines
Circle(6) = {3, 1, 6};
Line(7) = {3, 4};
Line(8) = {4, 7};
Line(9) = {7, 5};
Line(10) = {5, 6};
Line(21) = {7,11};

// Airfoil Lines
Spline(11) = {8,14,9};
Spline(12) = {9,15,10};
Spline(13) = {12,16,13};
Spline(14) = {13,17,8};
Line(19) = {10,11};
Line(20) = {11,12};

// Sharper Mesh
Transfinite Line {11,14} = 100 Using Progression 1.05;
Transfinite Line {-12,-13} = 100 Using Progression 1.05;
Transfinite Line {-21} = 100 Using Progression 1.05;

// Surfaces
Line Loop(15) = {7, 8, 9, 10, -6};
Line Loop(16) = {11,12,19,20,13,14};
Plane Surface(17) = {15, 16};
Plane Surface(18) = {16};
Extrude {0, 0, 1} {
Surface{17, 18};
Layers{1};
Recombine;
}
Extrude {0,0,1} {
Line{21};
}

// Naming Boundary Surfaces
Physical Surface("frontAndBack") = {77, 17};
Physical Surface("upperWall") = {36};
Physical Surface("lowerWall") = {48};
Physical Surface("inlet") = {52};
Physical Surface("outlet") = {44,40};

//Naming Airfoil Surfaces
Physical Surface("frontAndBackFoil") = {109, 18};
Physical Surface("upperFoil") = {76};
Physical Surface("lowerFoil") = {60};
Physical Surface("trailingedge") = {68, 64};

//Naming Volumes
Physical Volume("fluid") = {1};
Physical Volume("foil") = {2};

[CFD-Lover]

Have a look at this video;

https://www.youtube.com/watch?v=1A-b84kloFs

Please let me know if you are still struggling...