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getting errors while trying to plot

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Cesar Cardenas
Cesar Cardenas on 29 Mar 2023
Edited: Cesar Cardenas on 30 Mar 2023
I'm trying to plot this but I'm getting errors. Not sure how to fix them. Any help will be greatly appreciated. Thanks much.
% Toggle display for troubleshooting
% disp(['Calculating Streamwise Position ' ...
% num2str(LCVx) ' of ' num2str(Nx) ' (x = ' ...
% num2str(x(LCVx)) ' m)'])
% Solve for u at the next x location
% ENTER CODE HERE %
n=LCVx-1;
u_ns(1)=0;
u_ns(M)=Ue(n+1);
for mi =2:M-1
Q=nu*delta_x/u(mi)/delta_y^2;
P=1/2*delta_x/delta_y*v(mi)/u(mi);
u_ns(mi) = u(mi)+Ue(n)/u(mi)*(Ue(n+1)-Ue(n))+...
Q*(u(mi+1)-2*u(mi)+u(mi-1))-...
P*(u(mi+1)-u(mi-1));
end
% Solve for v at the next x location using the continuity equation
% ENTER CODE HERE %
v_ns(1)=0;
for mi =2:M
P=1/2*delta_y/delta_x;
v_ns(mi) = v_ns(mi-1)- ...
P*(u_ns(mi)-u(mi)+u_ns(mi-1)-u(mi-1));
end
% Update velocity profiles
u = u_ns;
v = v_ns;
% Calculate momentum thickness
% ENTER CODE HERE %
uf = @(z)interp1(y,u,z);
thetafun = @(z)uf(z).*(1-uf(z));
theta(LCVx) = integral(thetafun,min(y),max(y));
% Calculate skin friction coefficient
% ENTER CODE HERE %
cf(LCVx) =((nu/dy)/Uef (xstart)^2)*(4*u(2)-u(3));
if mod(n,500)==0
figure;subplot(1,2,1);plot(y,u_ns);subplot(1,2,2);plot(y,v_ns);
pause;
end
end uplots = u./Ue; yplots = y./theta; for x = xstart:0.2:xend figure hold on plot(y,u) figure hold on plot(yplots,uplots)
end
  5 Comments
Cris LaPierre
Cris LaPierre on 29 Mar 2023
Attach your text files to your post using the paperclip icon, and then we can say for certain.

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Answers (1)

Mathieu NOE
Mathieu NOE on 29 Mar 2023
Moved: Fangjun Jiang on 29 Mar 2023
the error message is quite clear
Unable to find file or directory 'negm_profiles.txt'.
this file is not in your directory
double check by typing in your command window
dir *.txt
if you need more help , it's genrally a good thing to share your data files along the code
  1 Comment
Mathieu NOE
Mathieu NOE on 29 Mar 2023
Moved: Fangjun Jiang on 29 Mar 2023
your code works fine with the provided txt files.
the next problem is here , here arrays size are not matching
uplots = u./Ue;
yplots = y./theta;
u and y are 300x1 arrays while Ue and theta are 8001x1 arrays
which one is the good size and how will you modify the code accordingly ?

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