How can I plot just a slice of circle that shows the degree of temperature

Hello,

I am using MatLab to study heat transfer and now I am developing a method for cylindrical coordinates. This is my code:

 clear 
 clc

 theta = linspace(-pi/8,pi/8,7); 
 r = linspace(0,1,10);
 [AA,RR] = meshgrid(theta,r);
 polar(AA,RR,'or');

How you can see, it's easy to understand what does it means. I made a grid to use FEM to solve.

When I run this cole the graphic shows:

There is nothing wrong with the image but I would like something look like it:

Probably it will be necessary to use other structure to plot the graphic, and not polar. Do you know what option do I have?

Cheers

Answer 1

[Star Strider]

I would use the pol2cart funciton:

theta = linspace(-pi/8,pi/8,7);
r = linspace(0,1,10);
[AA,RR] = meshgrid(theta,r);
[X,Y] = pol2cart(AA,RR);

figure(1)
plot(X,Y, 'or')
axis([-1.1  1.1    -1.1  1.1])
axis equal

Experiment with the axis function calls to get the plot appearance you want.

[yogan sganzerla]

Hi,

It worked very well. How could you see, I have 70 points and in each point, I will calculate the temperature at each point and time. In other words, I will have T(Theta,r,t) where t is the time.

The result that I would like to achieve is something like it.

When I was plotting with rectangular coordinates, I used pcolor(T(:,:,t)) and now with cylindrical coordinates? for example, in time 1, my multidimensional matrix is T(:,:,1)= 300 ºC and all the mesh grid should be red.

What should I do to plot it?

cheers

[Star Strider]

I have no idea how you calculate ‘Z’, so I created an expression for it to illustrate the correct approach:

theta = linspace(-pi/8,pi/8,7);
r = linspace(0,1,10);
[AA,RR] = meshgrid(theta,r);
[X,Y] = pol2cart(AA,RR);

Z = 1./(RR);                            % Create ‘Z’
figure(2)
surf(X, Y, Z)
colormap(jet(length(r)));
view([0  90])
axis equal

This actually gives something similar to the figure you illustrate.