splitting a shape into triangles

Question

Nasser Ramsis 2016-12-21

1
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https://ww2.mathworks.cn/matlabcentral/answers/317689-splitting-a-shape-into-triangles

评论： José-Luis 2016-12-21

Hello,

I'm writing a code to optimize some dimensions for a wing i'm designing. As part of the code i need to split up a 2D airfoil into triangles. I used a Delaunay triangulation and all the points are connected to 1 point. This is the code segment so far:

chord = 0.25;
nacanum = 12;
t = nacanum/100;
x=0:0.01:chord;
distratio = x/chord;
yt = 5*t*(0.2969*sqrt(distratio)-0.126*distratio-0.3516*distratio.^2+0.2843*distratio.^3-0.1015*distratio.^4);
at=delaunayTriangulation(x',yt');
tr=delaunay(x,yt);
triplot(at,x,yt);
triplot(tr,x,yt);

using delaunay and delaunay triangulation seem to plot the same figure but they appear somewhat different in the workspace can anyone explain what the difference is?

Also, all the points are connected to an origin point (1)

how can i change that? as in I want it to create the triangles side by side sharing only 1 or 2 points as opposed to all the triangles sharing an origin point. ( i hope that makes sense)

Thanks in advance

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Nasser Ramsis 2016-12-21

在 MATLAB Online 中打开

I realized the delaunay functions just number the points and connect them (i think). so i wrote this segment to create the same numbering but it wont plot.

for i=1:1:length(x)

    for j= 1:1:3
    tr(i,j)= i-1;
    end

end

for i=1:1:length(x)

tr(i,3)=i;

end

José-Luis 2016-12-21

I don't understand. What are you trying to accomplish here? Did you try what KSSV suggests?

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Answer 1

KSSV 2016-12-21

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/317689-splitting-a-shape-into-triangles#answer_248033

There is no difference between the two, they differ only in the way how the output is. Both of them creates nodal connectivity matrices and coordinates similar. In order to mesh your wing I suggest you to go through the following file exchange, which gives extra ordinary unstructured meshing.

https://in.mathworks.com/matlabcentral/fileexchange/25555-mesh2d-automatic-mesh-generation