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

[Paweł Maciakowski]

Hello Ashish,

You can play around the Line {#} In Surface {#} command for the wake region.

Regards,
Pawel

W dniu 2016-07-12 o 21:57, ashish bhole pisze:
> 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 <mailto: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 <mailto:guillaume.dilasser at cea.fr>
>
>     *De :*gmsh [mailto:gmsh-bounces at ace20.montefiore.ulg.ac.be
>     <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 <mailto: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
>
>
>
>
> _______________________________________________
> gmsh mailing list
> gmsh at onelab.info
> http://onelab.info/mailman/listinfo/gmsh
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://onelab.info/pipermail/gmsh/attachments/20160713/278b6784/attachment.html>