problem at smooting the spline

Question

onur karakurt 2021-6-23

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/863690-problem-at-smooting-the-spline

评论： onur karakurt 2021-7-11

采纳的回答： DGM

在 MATLAB Online 中打开

When trying smooting the leading edge of airfoil, nothing is changing. Leading edge looks like a arrow. not a circle.

How can ı smoot the leading edge of airfoil.?

x=[0.0   0.5     0.75    1.250   2.5     5.0     7.5     10      15      20      25      30      35      40      45      50      55      60      65      70      75      80      85      90      95      100]./100;
y=[0.0  0.394   0.475   0.594   0.795   1.090   1.322   1.518   1.828   2.066   2.245   2.375   2.459   2.498   2.487   2.420   2.290   2.106   1.881   1.623   1.339   1.038   0.729   0.430   0.165   0.0]./100;
erase=numel(x);
pp=spline(x,y);
xx=sort([x max(x)-0.005 max(x)-0.0075 max(x)-0.0125 max(x)-0.025 max(x)-0.075])
yy=ppval(pp,xx);
x=xx;y=yy;
x=[flip(x) x]; x(numel(xx))=[];
y=[flip(y) -(y)]; y(numel(xx))=[];
plot(x,y)
axis equal

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onur karakurt 2021-6-23

I opened cftool program. is there any function for curvefitting toll with fourier8 , without openning tool page

DGM 2021-6-23

I'm not that familiar with the depths of the CFT, and I'm not really sure how one would use cftool for this case.

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Answer 1

DGM 2021-6-23

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/863690-problem-at-smooting-the-spline#answer_731975

编辑：DGM 2021-6-23

在 MATLAB Online 中打开

You could try doing something like this instead of trying to enforce endslopes

x = [0.0   0.5     0.75    1.250   2.5     5.0     7.5     10      15      20      25      30      35      40      45      50      55      60      65      70      75      80      85      90      95      100]./100;
y = [0.0  0.394   0.475   0.594   0.795   1.090   1.322   1.518   1.828   2.066   2.245   2.375   2.459   2.498   2.487   2.420   2.290   2.106   1.881   1.623   1.339   1.038   0.729   0.430   0.165   0.0]./100;
% build a single curve
x = [fliplr(x(2:end-1)) x(2:end-1)];
y = [fliplr(y(2:end-1)) -y(2:end-1)];
% for sake of doing this in polar, x needs to be offset temporarily
% for sake of getting spline to interpolate well, temporarily adjust aspect ratio
xos = 0.5;
ysc = 40;
x = x-xos;
y = y*ysc;
% convert to polar coordinates
r = sqrt(x.^2 + y.^2);
th = atan2(y,x);
th(th<0) = 2*pi+th(th<0);
% do the interpolation
thf = linspace(0,2*pi,1000);
rf = spline(th,r,thf);
% convert back, reposition/rescale, plot
xf = [1 rf.*cos(thf)+xos 1];
yf = [0 rf.*sin(thf) 0]/ysc;
plot(xf,yf); axis equal