[Gmsh] Problem with Boundary Layer around 2D airfoil with sharp trailing edge

[ashish bhole]

Hello Guillaume,

Thank you so much for you help.

Can I extend the same boundary layer into wake region? I tried doing the
same by drawing a line from trailing edge to farfield and creating boundary
layer around it. But I have not succeeded yet.

-- With Regards
Ashish




On Tue, Jul 12, 2016 at 12:36 PM, DILASSER Guillaume <
Guillaume.DILASSER at cea.fr> wrote:

> Hello Ashish,
>
>
>
> You can add to the BoundaryLayer definition the property
> “Field[1].FanNodesList = {1,n} ;” to get rid of the weird behavior of the
> mesh around the tips of the foil. Somehow, the 2D blossom recombination
> algorithm does not like when you do that so replace it with the standard
> one using “Mesh.RecombinationAlgorithm = 0 ;”. Both modifications are done
> in the enclosed file. Finally, you may want to increase the mesh density at
> the front of the foil to better match the geometry there.
>
>
>
> Sincerely Yours,
>
>
>
> Guillaume DILASSER
>
> Doctorant SACM / LEAS
>
> CEA - Centre de Saclay - Bât.123 - PC 319c
>
> 91191 Gif sur Yvette Cedex - France -
>
>
>
> guillaume.dilasser at cea.fr
>
>
>
>
>
> *De :* gmsh [mailto:gmsh-bounces at ace20.montefiore.ulg.ac.be] *De la part
> de* ashish bhole
> *Envoyé :* lundi 11 juillet 2016 19:02
> *À :* gmsh at onelab.info
> *Objet :* [Gmsh] Problem with Boundary Layer around 2D airfoil with sharp
> trailing edge
>
>
>
> Hello All,
>
> I am new at using gmsh. I want to generate a mesh (unstructured) around 2D
> airfoil with sharp trailing edge. When I use Boundary Layer field in gmsh,
> it generates boundary layer but with undesirable intersections. I have
> attached my .geo file here. Currently, I have commented Boundary Layer
> field lines in the script.
>
> Please share idea how can I make it work correctly.
>
> Thank you.
>
> ------------------------------------
> Mesh.RecombineAll = 1;
>
> Li = 50.0; // distance of inflow boundary from origin
> Lo = 50.0; // distance of outflow boundary from origin
>
> n  = 50; // points on upper/lower surface of airfoil used to define airfoil
>          // These points may not appear in the mesh.
>
> lc1 = 10.0;
> lc2 = 0.05;
>
> m = 2*n - 2; // total number of points on airfoil without repetition
>              // LE and TE points are common to upper/lower surface
>
> nle = n; // point number of LE = no. of points on upper surface
>          // Point(1) is trailing edge
>
> // NACA0012 profile
> // formula taken from http://turbmodels.larc.nasa.gov/naca0012_val.html
> Macro NACA0012
>    x2 = x * x;
>    x3 = x * x2;
>    x4 = x * x3;
>    y = 0.594689181*(0.298222773*Sqrt(x)
>        - 0.127125232*x - 0.357907906*x2 + 0.291984971*x3 - 0.105174606*x4);
> Return
>
> // put points on upper surface of airfoil
> For i In {1:n}
>    theta = Pi * (i-1) / (n-1);
>    x = 0.5 * (Cos(theta) + 1.0);
>    Call NACA0012;
>    Point(i) = {x, y, 0.0, lc2};
>    xx[i] = x;
>    yy[i] = y;
> EndFor
>
> // put points on lower surface of airfoil, use upper surface points and
> reflect
> For i In {n+1:m}
>    Point(i) = {xx[2*n-i], -yy[2*n-i], 0.0, lc2};
> EndFor
>
> Spline(1) = {1:n};
> Spline(2) = {n:m, 1};
>
> Point(1000) = {1.0, Li, 0.0,lc1};
> Point(1001) = {0.0, Li, 0.0,lc1};
> Point(1002) = {-Li, 0.0, 0.0,lc1};
> Point(1003) = {0.0, -Li, 0.0,lc1};
> Point(1004) = {1.0, -Li, 0.0,lc1};
>
> Point(1005) = {Lo, 0.0, 0.0,lc1};
> Point(1006) = {Lo, Li, 0.0,lc1};
> Point(1007) = {Lo, -Li, 0.0,lc1};
>
> Line(5) = {1000, 1001};
> Circle(6) = {1001, nle, 1002};
> Circle(7) = {1002, nle, 1003};
> Line(8) = {1003, 1004};
> Line(13) = {1005, 1006};
> Line(14) = {1005, 1007};
> Line(15) = {1006, 1000};
> Line(16) = {1007, 1004};
>
> Line Loop(1) = {1,2};
> Line Loop(2) = {5,6,7,8,-16,-14,13,15};
>
> Plane Surface(201) = {2,1};
>
> /*
> //Define Boundary Layer
> Field[1] = BoundaryLayer;
> Field[1].EdgesList = {1,2};
> Field[1].NodesList = {1,m};
> Field[1].hfar = 0.05;
> Field[1].hwall_n = 0.009;
> Field[1].thickness = 0.2;
> Field[1].ratio = 1.1;
> Field[1].AnisoMax = 10;
> Field[1].Quads = 1;
> Field[1].IntersectMetrics = 0;
> BoundaryLayer Field = 1;
> */
> ------------------------------------
>
> -- With Reagrds
>
> Ashish Bhole
>
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