MATLAB: How to solve an ODE with an array using ODE45

arrayodeode45

I have an ODE, udY/dx=S , where Y and S are arrays , how do I solve it using ODE45 ???

Best Answer

% Solution 4: Chemical Species Concentration as a Function of Axial Distance
clc
clear
% Constants

L  = 0.12;
N  = 39;
T(1:N) = 750;
delx     = L/(N-1);
xspan    = 0:delx:0.12;
C0       = [0.52 0.99 0.0];
% ODE 45 Code
[x,C]=ode45('hw2_4',xspan,C0);
% Plots
subplot(2,1,1);
plot(x,C(:,1),'b--o',x,C(:,2),'g--+',x,C(:,3),'r--s')
legend('C_{CO}','C_{O2}','C_{CO2}')
xlabel('Axial (x) Direction [m]')
ylabel('Concentrations [mol/m^3]')
title('Molar Concentration vs Distance')
Function File:
function dcdx=hw2_4(x,C)
% Constants
u = 1.5;
A  = 2.2e10;
Ea = 130000;
Ru = 8.3145;
T  = 750;
% Rate Constants
R(1)     = -A * (exp(-Ea / (Ru*T))) * C(1) * sqrt(C(2)); 
R(2)     = 0.5 * R(1);  
R(3)     = -R(1);
dcdx     = [R(1);R(2);R(3)]/u;
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