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huitetquatre January 26, 2013 03:16

[wing mesh with gmsh]
 
Hi,

My main objective is to "create" a wing. I've already analysed different Naca profiles without any problems. The second step is to analyse a complete wing.
I'm actually generating points with a specific pg, then the .geo file is generated, then the mesh is created by gmsh and I finally apply the gmshToFoam command.

The generated mesh seams to be good but the checkMesh failed.

A simple geo sample:
Code:

xmin =  0;
xmax =  1;
ymin = -1;
ymax =  1;
zmin = -1;
zmax =  2;

box_lc = 0.5;
lc = 0.01;

Point(1) = { xmin, ymin, zmin, box_lc};
Point(2) = { xmin, ymax, zmin, box_lc};
Point(3) = { xmin, ymax, zmax, box_lc};
Point(4) = { xmin, ymin, zmax, box_lc};

Line(1) = {1, 2};
Line(2) = {2, 3};
Line(3) = {3, 4};
Line(4) = {4, 1};

Line Loop(1) = {1, 2, 3, 4};

Plane Surface(1) = {1};

tmp[] = Extrude {xmax-xmin, 0, 0} {
  Surface{1};
};
Delete { Volume{tmp[1]}; }
Delete { Surface{1}; }

// ----------
l = 0.2;
h = 0.2;
w = 0.5;

Point(101) = {xmin, -l, 0, lc};
Point(102) = {xmin,  l, 0, lc};
Point(103) = {xmin,  0, h, lc};

Point(201) = {xmin+w, -l, 0, lc};
Point(202) = {xmin+w,  l, 0, lc};
Point(203) = {xmin+w,  0, h, lc};

Line(101) = {101, 102};
Line(102) = {102, 103};
Line(103) = {103, 101};

Line(201) = {201, 202};
Line(202) = {202, 203};
Line(203) = {203, 201};

Line(301) = {101, 201};
Line(302) = {102, 202};
Line(303) = {103, 203};

Line Loop(2) = {101, 102, 103};
Line Loop(3) = {201, 202, 203};

Line Loop(11) = {301, 201, -302, -101};
Line Loop(12) = {302, 202, -303, -102};
Line Loop(13) = {303, 203, -301, -103};


Plane Surface(100) = {1, 2}; // Left
Plane Surface(101) = {3};    // Wing right

Plane Surface(201) = {11};
Plane Surface(202) = {12};
Plane Surface(203) = {13};

// Right = 26
// Front = 25
// Top  = 21
// Back  = 17
// Bot  = 13

Surface Loop(1000) = {26, 25, 21, 17, 13, 100, 201, 202, 203, 101};
Volume (1000) = {1000};

Physical Surface("front")  = {25};
Physical Surface("back")    = {17};
Physical Surface("top")    = {21};
Physical Surface("bottom")  = {13};
Physical Surface("left")    = {100};
Physical Surface("right")  = {26};

Physical Surface("foil")    = {201, 202, 203, 101};

Physical Volume("internal") = {1000};

checkMesh -allTopology -allGeometry :
Code:

Create polyMesh for time = 0

Time = 0

Mesh stats
    points:          8990
    faces:            72001
    internal faces:  58059
    cells:            32515
    boundary patches: 7
    point zones:      0
    face zones:      0
    cell zones:      1

Overall number of cells of each type:
    hexahedra:    0
    prisms:        0
    wedges:        0
    pyramids:      0
    tet wedges:    0
    tetrahedra:    32515
    polyhedra:    0

Checking topology...
    Boundary definition OK.
 ***Total number of faces on empty patches is not divisible by the number of cells in the mesh. Hence this mesh is not 1D or 2D.
    Cell to face addressing OK.
    Point usage OK.
    Upper triangular ordering OK.
    Face vertices OK.
    Topological cell zip-up check OK.
    Face-face connectivity OK.
  <<Writing 103 cells with with two non-boundary faces to set twoInternalFacesCells
    Number of regions: 1 (OK).

Checking patch topology for multiply connected surfaces ...
    Patch              Faces    Points  Surface topology                  Bounding box
    bottom              8        9        ok (non-closed singly connected)  (0 -1 -1) (1 1 -1)
    back                16      15      ok (non-closed singly connected)  (0 1 -1) (1 1 2)
    top                6        8        ok (non-closed singly connected)  (0 -1 2) (1 1 2)
    front              16      15      ok (non-closed singly connected)  (0 -1 -1) (1 -1 2)
    right              44      31      ok (non-closed singly connected)  (1 -1 -1) (1 1 2)
    left                607      359      ok (non-closed singly connected)  (0 -1 -1) (0 1 2)
    foil                13245    6671    ok (non-closed singly connected)  (0 -0.2 0) (0.5 0.2 0.2)

Checking geometry...
    Overall domain bounding box (0 -1 -1) (1 1 2)
    Mesh (non-empty, non-wedge) directions (0 1 1)
    Mesh (non-empty) directions (0 1 1)
 ***Number of edges not aligned with or perpendicular to non-empty directions: 45693
  <<Writing 8990 points on non-aligned edges to set nonAlignedEdges
    Boundary openness (-2.48715e-18 1.85141e-18 6.14172e-19) OK.
    Max cell openness = 1.42973e-16 OK.
    Max aspect ratio = 31.7252 OK.
    Minumum face area = 1.67583e-05. Maximum face area = 0.388435.  Face area magnitudes OK.
    Min volume = 8.84634e-10. Max volume = 0.043476.  Total volume = 5.98.  Cell volumes OK.
    Mesh non-orthogonality Max: 86.2608 average: 29.571
  *Number of severely non-orthogonal faces: 314.
    Non-orthogonality check OK.
  <<Writing 314 non-orthogonal faces to set nonOrthoFaces
    Face pyramids OK.
 ***Max skewness = 6.06065, 96 highly skew faces detected which may impair the quality of the results
  <<Writing 96 skew faces to set skewFaces
    Coupled point location match (average 0) OK.
    Face tets OK.
    Min/max edge length = 0.00553551 1.20185 OK.
    All angles in faces OK.
    All face flatness OK.
    Cell determinant (wellposedness) : minimum: 3.80836e-06 average: 0.494671
 ***Cells with small determinant found, number of cells: 133
  <<Writing 133 under-determined cells to set underdeterminedCells
    Concave cell check OK.

Failed 3 mesh checks.

End


What's wrong ? How can I solve this problem ?


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