I want to make the figure hanger look like the attached picture. The code is shown below.

 clc
L=3;% L=y fare away the the plate (boundary layer)
T=2;%Final time
maxk=500;%Number of time steps
dt=T/maxk;
n=50;%Number of space steps
dy=L/n;
diff=0.25;
b=diff*dt/(dy*dy);
%b=0.1;
%initial condition of velocity
for i=1:n+1
    y(i)=(i-1)*dy;
    u(1,1)=0;
end
%Boundary condition
for k=1:maxk+1
    u(1,k)=1;
    u(n+1,k)=0;
end
for k=1:maxk %time loop
    for i=2:n %space loop
        u(i,k+1) =u(i,k)+b*(u(i-1,k)+u(i+1,k)-2.*u(i,k));
    end
end
%Ploting
figure(1)
%plot(y,u(:,1),'-',y,u(:,100),'-',y,u(:,300),'-',y,u(:,600),'-')
plot(y,u(:,50),'-',y,u(:,100),'-',y,u(:,200),'-',y,u(:,250),'-')
%legend('dt=50','dt=100','dt=200','dt=250')
title('Velocity in the boundary layer')
xlabel('y')
ylabel('velocity')

[T K]

 The picture is attached

[Rena Berman]

(Answers Dev) Restored edit

Answer 1

[Walter Roberson]

Instead of using plot() use surf(), with 'edgecolor', 'none', and with 'alphadata' set to a constant repeated the same size as u, and with AlphaDataMapping 'none' and with 'FaceAlpha', 'flat'

https://www.mathworks.com/help/matlab/creating_plots/add-transparency-to-graphics-objects.html

[T K]

Can you write the code commands please?

[Walter Roberson]

surf(x, y, u, 'edgecolor', 'none', 'AlphaDataMapping', 'none', 'FaceAlpha', 'flat', 'Alpha', 0.8 * ones(size(u)));
hold on

This would be in a loop in which you changed whatever it is you need to change, creating a new u matrix each time.

[T K]

Please doctor walter Roberson, when writing the attached code, an error appeared:

Undefined function or variable 'x'.

Error in Untitled (line 24)

surf(x(i), y(i), u(i), 'edgecolor', 'none', 'AlphaDataMapping', 'none', 'FaceAlpha', 'flat', 'Alpha', 0.8 * ones(size(u(i))));

code attached

clc

L=3;

T=2;

maxk=500;

dt=T/maxk;

n=50;%Number of space steps

dy=L/n;

diff=0.25;

b=diff*dt/(dy*dy);

%initial condition

for i=1:n+1

y(i)=(i-1)*dy;

u(1,1)=0;

end

%Boundary condition

for k=1:maxk+1

u(1,k)=1;

u(n+1,k)=0;

end

for k=1:maxk %time loop

for i=2:n %space loop

u(i,k+1) =u(i,k)+b*(u(i-1,k)+u(i+1,k)-2.*u(i,k));

surf(x(i), y(i), u(i), 'edgecolor', 'none', 'AlphaDataMapping', 'none', 'FaceAlpha', 'flat', 'Alpha', 0.8 * ones(size(u(i))));

hold on

end

end

%Ploting

figure(1)

plot(y,u(:,50),'-',y,u(:,100),'-',y,u(:,200),'-',y,u(:,250),'-')

legend('dt=50','dt=100','dt=200','dt=250')

title('Velocity in the boundary layer')

xlabel('y')

ylabel('velocity')