How can I solve in the error?

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Myo Gyi
Myo Gyi 2022-12-20
评论： Myo Gyi 2022-12-20
clear all, clc; % clear all memory and variables
x = linspace(-1,1); % create linear spacing in x-direction
y = linspace(-1,1); % create linear spacing in y-direction
%initialise velocity
U = 1.; %freestream velocity
%looping in i and j-directions
for i = 1:length(x)
for j = 1:length(y)
%create x & y space
xx(i,j) = x(i);
yy(i,j) = y(j);
%calculate radius from x & y
rad(i,j) = sqrt(x(i)^2 + y(j)^2);
% calculate angle from x and y
if x(i) > 0
theta(i,j) = atan(y(j)/x(i));
elseif x(i) <0 && y(j) >= 0
theta(i,j) =atan(y(j)/x(i))+pi;
elseif x(i) < 0 && y(j) < 0
theta(i,j) = atan(y(j)/x(i))-pi;
elseif x(i) == 0 && y(j) < 0
theta(i,j) = pi/2;
else
theta(i,j) = – pi/2;
end
% calculate stream function using polar coordinate system
psi(i,j) = U *rad(i,j)*sin(theta(i,j));
% calculate velocity potential using polar coordinate system
phi(i,j) = U*rad(i,j)*cos(theta(i,j));
end
end
%plotting
contourf(xx,yy,psi,-1:0.2:1,’k’,’LineWidth’,1.5), hold on % plot stream function for range -1:0.1:1
contour(xx,yy,phi,-1:0.2:1,’r’,’LineWidth’,1.5) % plot velocity potential for range -1:0.2:1
axis image, hold off
legend(‘streamlines’,’potential’)
title(‘Uniform stream in x-direction’)
xlabel(‘x-coordinate’), ylabel(‘y-coordinate’)
axis square;
% end of Octave program
  2 个评论
Karim
Karim 2022-12-20
Which error?
After correcting the apostrophes and the minus sign the code appears to run without issues?
Myo Gyi
Myo Gyi 2022-12-20
Thank you sir... Can You repair for my code sir.

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回答（1 个）

Stephan
Stephan 2022-12-20
Ran in:
%clear all, clc; % clear all memory and variables
x = linspace(-1,1); % create linear spacing in x-direction
y = linspace(-1,1); % create linear spacing in y-direction
%initialise velocity
U = 1.; %freestream velocity
%looping in i and j-directions
for i = 1:length(x)
for j = 1:length(y)
%create x & y space
xx(i,j) = x(i);
yy(i,j) = y(j);
%calculate radius from x & y
rad(i,j) = sqrt(x(i)^2 + y(j)^2);
% calculate angle from x and y
if x(i) > 0
theta(i,j) = atan(y(j)/x(i));
elseif x(i) <0 && y(j) >= 0
theta(i,j) =atan(y(j)/x(i))+pi;
elseif x(i) < 0 && y(j) < 0
theta(i,j) = atan(y(j)/x(i))-pi;
elseif x(i) == 0 && y(j) < 0
theta(i,j) = pi/2;
else
theta(i,j) = -pi/2;
end
% calculate stream function using polar coordinate system
psi(i,j) = U *rad(i,j)*sin(theta(i,j));
% calculate velocity potential using polar coordinate system
phi(i,j) = U*rad(i,j)*cos(theta(i,j));
end
end
%plotting
contourf(xx,yy,psi,-1:0.2:1,'k','LineWidth',1.5), hold on % plot stream function for range -1:0.1:1
contour(xx,yy,phi,-1:0.2:1,'r','LineWidth',1.5) % plot velocity potential for range -1:0.2:1
axis image, hold off
legend('streamlines','potential')
title('Uniform stream in x-direction')
xlabel('x-coordinate'), ylabel('y-coordinate')
axis square;
  1 个评论
Myo Gyi
Myo Gyi 2022-12-20
Thanks Sir.... Can I get more pitcure like this side
https://people.utm.my/ridhwan/teaching/skme-3333-aerodynamics/potential-flow/

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