[Gmsh] Problem with Boundary Layer meshing

[Nguyen Anh Khoa Doan]

Hello GMSH users,

I have a problem regarding the use of the BoundaryLayer feature in gmsh for
a 2D mesh.
I have tried to create a boundary layer mesh around a square and use the
FanNodesLists option to get a fan around the corners. However this creates
additional quad-cells for some parts of the fan and thus, I get triangular
cells with a really bad aspect ratio just beyond the boundary layer (see
picture attached). The same problem arises when trying to mesh the Boundary
Layer around an airfoil at the TE (see picture).

The code for the square:
// Gmsh project created on Fri May 16 14:29:34 2014
Point(1) = {-4, -4, 0, 1.0};
Point(2) = {-4, 4, 0, 1.0};
Point(3) = {4, 4, 0, 1.0};
Point(4) = {4, -4, 0, 1.0};

Point(5) = {-1, -1, 0, 0.1};
Point(6) = {1, -1, 0, 0.1};
Point(7) = {1, 1, 0, 0.1};
Point(8) = {-1, 1, 0, 0.1};

Line(1) = {1, 2};
Line(2) = {2, 3};
Line(3) = {3, 4};
Line(4) = {4, 1};
Line(5) = {5, 6};
Line(6) = {6, 7};
Line(7) = {7, 8};
Line(8) = {8, 5};
Line Loop(9) = {1, 2, 3, 4};
Line Loop(10) = {6, 7, 8, 5};

Plane Surface(11) = {9, 10};

Field[1] = BoundaryLayer;
Field[1].EdgesList = {5,6,7,8};
//Field[1].NodesList = {5,6,7,8};
Field[1].FanNodesList = {5,6,7,8};
Field[1].hfar = 0.05;
Field[1].hwall_n = 0.001;
Field[1].hwall_t = 0.003;
Field[1].ratio = 1.1;
Field[1].thickness = 0.01;
Field[1].Quads = 1;
BoundaryLayer Field = 1;

Any help would be extremely welcome.

Regards,

Nguyen Anh Khoa DOAN
Last year dual degree student - Université Libre de Bruxelles - SUPAERO
Aerospace Engineering - Major: Propulsion & Complex Systems and Simulation
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