# How to plot graph?

4 views (last 30 days)
Nur Nadhirah Syed Malik on 30 Dec 2021
Answered: Prachi Kulkarni on 11 Jan 2022
Hi, I really need help. I want to plot graph where the x-axis is the radius (r) and the y-axis is the velocity (u). I want the x-axis the range is from 0 to 1. Can anyone help me, pleaseee
%Parameters to define the governing casson fluid equation and the
%parameters value range
L= 1; % Length of the artery
maxk= 10; % Number of time steps
tmax = 0.1; % Maximum time
delta_t = tmax/maxk; % Time step
n = 10; % Number of space steps
delta_r = L/n; % Radial direction
Beta1 = 0.025; % Casson fluid parameter
A0 = 0.2; % Amplitude of systolic pressure gradient
A1 = 0.4; % Amplitude of diastolic pressure gradient
omega = pi/4;
r= 1;
%Initial conditions of velocity
for i = 1:n+1
u(i,1) = 0;
disp(u(i,1));
end
% Boundary conditions
for j=1:maxk+1
u(1,j) = 0;
u(n,j) = 0;
end
% Implementation of the explicit
for j=1:maxk % Time Loop
for i=2:n % Space Loop
S10 = (u(2,j)-2*u(1,j)+u(2,j))/((delta_r)^2);
S20 = (u(2,j)-u(1,j))/(delta_r);
u(1,j+1) = u(1,j) + delta_t*(A0 + A1*cos(omega*t) + Beta1*((S10) + (1/r)* (S20)));
disp(u(1,j+1))
S1 = (u(i+1,j)-2*u(i,j)+u(i-1,j))/((delta_r)^2);
S2 = (u(i+1,j)-u(i,j))/(delta_r);
u(i,j+1) = u(i,j) + delta_t*(A0 + A1*cos(omega*t) + Beta1*((S1) + (1/r)* (S2)));
disp(u(i,j+1))
S1n = (u(n+1,j)-2*u(n,j)+u(n-1,j))/((delta_r)^2);
S2n = (u(n+1,j)-u(n,j))/(delta_r);
u(n,j+1) = u(n,j) + delta_t*(A0 + A1*cos(omega*t) + Beta1*((S1n) + (1/r)* (S2n)));
disp(u(n,j+1))
end
end
%Graphical representation of the velocity at different selected times
Walter Roberson on 30 Dec 2021
I suggest that you are trying to do something that cannot be done, and need to instead change what you are trying to do.
At the moment, you have an r dimension, a time dimension, a spatial dimension, and a result. That is a 3D array of data, which would require a 4 dimensional plot. Such plots are difficult to interpret, but you can try volumeViewer() or slice() or isosurface()

Prachi Kulkarni on 11 Jan 2022
Hi,
If you want the plots for each timepoint in separate figures, you can use the following code.
r_range = 0:delta_r:1;
for j=1:maxk+1
figure, plot(r_range,u(:,j));
end
If you want the plots for all timepoints in the same plot, you can use the following code.
figure, plot(r_range,u);

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