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<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">Hello Ashish,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">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.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">Sincerely Yours,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Tahoma",sans-serif;color:#000099">Guillaume DILASSER</span><span style="font-size:10.0pt;font-family:"Tahoma",sans-serif;color:#000099"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:7.5pt;font-family:"Arial",sans-serif;color:#000099">Doctorant SACM / LEAS<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:7.5pt;font-family:"Arial",sans-serif;color:#000099">CEA - Centre de Saclay - Bât.123 - PC 319c</span><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#000099"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:7.5pt;font-family:"Arial",sans-serif;color:#000099">91191 Gif sur Yvette Cedex - France -</span><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#000099"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:7.5pt;font-family:"Arial",sans-serif;color:#000099"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:7.5pt;font-family:"Arial",sans-serif;color:#000099"><a href="mailto:guillaume.dilasser@cea.fr">guillaume.dilasser@cea.fr</a><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><b><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif">De :</span></b><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif"> gmsh [mailto:gmsh-bounces@ace20.montefiore.ulg.ac.be]
<b>De la part de</b> ashish bhole<br>
<b>Envoyé :</b> lundi 11 juillet 2016 19:02<br>
<b>À :</b> gmsh@onelab.info<br>
<b>Objet :</b> [Gmsh] Problem with Boundary Layer around 2D airfoil with sharp trailing edge<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><span lang="EN-US">Hello All,<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><span lang="EN-US">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.
<o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US">Please share idea how can I make it work correctly.<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><span lang="EN-US">Thank you.<br>
<br>
------------------------------------<br>
Mesh.RecombineAll = 1;<br>
<br>
Li = 50.0; // distance of inflow boundary from origin<br>
Lo = 50.0; // distance of outflow boundary from origin<br>
<br>
n = 50; // points on upper/lower surface of airfoil used to define airfoil<br>
// These points may not appear in the mesh.<br>
<br>
lc1 = 10.0;<br>
lc2 = 0.05;<br>
<br>
m = 2*n - 2; // total number of points on airfoil without repetition<br>
// LE and TE points are common to upper/lower surface<br>
<br>
nle = n; // point number of LE = no. of points on upper surface<br>
// Point(1) is trailing edge<br>
<br>
// NACA0012 profile<br>
// formula taken from </span><a href="http://turbmodels.larc.nasa.gov/naca0012_val.html"><span lang="EN-US">http://turbmodels.larc.nasa.gov/naca0012_val.html</span></a><span lang="EN-US"><br>
Macro NACA0012<br>
x2 = x * x;<br>
x3 = x * x2;<br>
x4 = x * x3;<br>
y = 0.594689181*(0.298222773*Sqrt(x) <br>
- 0.127125232*x - 0.357907906*x2 + 0.291984971*x3 - 0.105174606*x4);<br>
Return<br>
<br>
// put points on upper surface of airfoil<br>
For i In {1:n}<br>
theta = Pi * (i-1) / (n-1);<br>
x = 0.5 * (Cos(theta) + 1.0);<br>
Call NACA0012;<br>
Point(i) = {x, y, 0.0, lc2};<br>
xx[i] = x;<br>
yy[i] = y;<br>
EndFor<br>
<br>
// put points on lower surface of airfoil, use upper surface points and reflect<br>
For i In {n+1:m}<br>
Point(i) = {xx[2*n-i], -yy[2*n-i], 0.0, lc2};<br>
EndFor<br>
<br>
Spline(1) = {1:n};<br>
Spline(2) = {n:m, 1};<br>
<br>
Point(1000) = {1.0, Li, 0.0,lc1};<br>
Point(1001) = {0.0, Li, 0.0,lc1};<br>
Point(1002) = {-Li, 0.0, 0.0,lc1};<br>
Point(1003) = {0.0, -Li, 0.0,lc1};<br>
Point(1004) = {1.0, -Li, 0.0,lc1};<br>
<br>
Point(1005) = {Lo, 0.0, 0.0,lc1};<br>
Point(1006) = {Lo, Li, 0.0,lc1};<br>
Point(1007) = {Lo, -Li, 0.0,lc1};<br>
<br>
Line(5) = {1000, 1001};<br>
Circle(6) = {1001, nle, 1002};<br>
Circle(7) = {1002, nle, 1003};<br>
Line(8) = {1003, 1004};<br>
Line(13) = {1005, 1006};<br>
Line(14) = {1005, 1007};<br>
Line(15) = {1006, 1000};<br>
Line(16) = {1007, 1004};<br>
<br>
Line Loop(1) = {1,2};<br>
Line Loop(2) = {5,6,7,8,-16,-14,13,15};<br>
<br>
Plane Surface(201) = {2,1};<br>
<br>
/*<br>
//Define Boundary Layer<br>
Field[1] = BoundaryLayer;<br>
Field[1].EdgesList = {1,2};<br>
Field[1].NodesList = {1,m};<br>
Field[1].hfar = 0.05;<br>
Field[1].hwall_n = 0.009;<br>
Field[1].thickness = 0.2;<br>
Field[1].ratio = 1.1;<br>
Field[1].AnisoMax = 10;<br>
Field[1].Quads = 1;<br>
Field[1].IntersectMetrics = 0;<br>
BoundaryLayer Field = 1;<br>
*/<br>
------------------------------------<br>
<br>
<o:p></o:p></span></p>
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<p class="MsoNormal">-- With Reagrds<o:p></o:p></p>
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<p class="MsoNormal">Ashish Bhole <o:p></o:p></p>
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