Attempted to access C2(3); index out of bounds because numel(C2)=2.

Dear Sir

I am trying to solve this code for the last few days but getting different kinds of errors. Now when I run this code I got error message 'Attempted to access C2(3); index out of bounds because numel(C2)=2.'. Please help me for solving this problem.

global Vl asl Vm Da K h Ksl n V v
clc
clear all

n = 100;
Lt   = 4;            % Length(cm)
rt   = 1;          % radius(cm)
Vl  = 3.14*rt^2*Lt;       % Volume(cm3)
asl  = 880;              % Specific surface area(cm2/g)
Vm = 1;
D   = 7.2*10^-5;
por = 0.3;
Da  =D*por^0.5;
V=5;
v=20;
Ea  = 61000;            % Activation Energy(J/mol)
R   = 8.314;            % Universal gas constant( J/mol/K)
T = 303.15;
K = 0.19*exp(-Ea/(R*T));                    %%rate constant                  
h  = Lt/(n-1);                                %%grid spacing or distance
Ksl = 10^-5;                                  %%coeff.(cm/s)   
C2=[0;0.3*ones(n,1);0.3];
C1=[0;10^-4*ones(n,1);10^-4];
C=[C1;C2];
 [t,C1]=ode45(@tube_fun_ode_f,[0 10^5],[10^-4,0.3]); 

function dC = tube_fun_ode_f(t,C)
global h K Da Ksl Vl asl Vm n v
C1=[0;10^-4*ones(n,1);10^-4];
C2=[0;0.3*ones(n,1);0.3];
C=[C1;C2];

for i=1
dC(1)=[10^-5; Vm*(Ksl*K*asl/(Ksl*asl-Vl*K))*C1(i)];
end

for i=2:length(C)-1
dC(i)=[(C2(i+1)*Da/h^2-C2(i)*v(i)/2*h)*C1(i+1)-(C2(i+1)*Da/h^2+C2(i)*Da/h^2)*C1(i)+(C2(i)*Da/h^2+C2(i)*v(i)/2*h)*C1(i-1)+C2(i)*K*C1(i); Vm*(Ksl*K*asl/(Ksl*asl-Vl*K))*C1(i)];
end

for i=length(C)
dC(end)=[dC(end-1); Vm*(Ksl*K*asl/(Ksl*asl-Vl*K))*C1(i)];
end

here is my original problem which I want to solve after discretization.

dC1/dt=d/dx(De*C2*(dC1/dx))-V*(dC1/dx)+(Ksl*asl/(Ksl*asl-Vl*K))*C1*C2

dC2/dt=Vm*( Ksl*asl/(Ksl*asl-Vl*K))*C1

t=0        C1=0          all x
t>0        C1=0          at x=0
T>0       dC1/dx=0      at x=L
at t=0    C2=0

--
Shashikant

Answer 1

[David Sanchez]

I think you problem ( at least one of them ) lies on:

dC(1)=[10^-5; Vm*(Ksl*K*asl/(Ksl*asl-Vl*K))*C1(i)];

inside your tube_fun_ode_f function. Why do you use a for_loop if you only have one value ( for i=1 ). You are assigning a 2D array to dC(1). What's the point of your semicolon ( ; )?