Must be a positive integer or logical
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Im having trouble with this code I need to the matrix to go up in steps of either 0.0052 for the time or to complete the loop t<t_2 in steps of 0.0052 or 1:(t_2/del_t).
%Aluminium Material Properties%
clear all
close all
clc
rho = 2700 ; %kg/m^3 Density
k = 170 ; %
cp = 910 ; %
alpha = k/(rho*cp); %
L_d = 0.0047; %m Diameter
L_x = 0.047; %m Length in x direction
L_r = L_d/2; %m Radius
n_r = 2; % Nodes in r direction
n_x = 40; % Nodes in x direction
del_x = L_x/(n_x-1); %m Spacing of Nodes
T_h = 27; %C Temperature of Hot Side
T_i = 19; %C Initial Temperature
t_2 = 180; %s Simulation Time
t(1) = 0; %s Initial Time
Fo_1 = 0.25; % Fourier Number Stability 0.25 For 3D
del_t = (Fo_1*del_x^2)/alpha; % Calculate time step using Fourier Number for Stability
h = 5;
%Set Inital Matrices Temp
T(1:n_r+2,1:n_x+2,1) = T_i; %Sets matrix dimensions and sets it to 19 C
Fo = alpha*del_t/(del_x.^2) ; % Fourier Number
Bi = h*del_x/k ; % Biot Number
if Fo > 0.25
fprintf('Fo Number to big, code unstable \n \n') %Check if Fo is acceptable
elseif Fo*(1-Bi) > 0.25
fprintf('Bi Number to big, code unstable') %Check if Bi is acceptable
end
k = 1;
while t<t_2 % Time Loop
for r=1:n_r+2 % Space Loop r direction
for x=1:n_x+2 % Space Loop x direction
if x==1 || x==42 || r==1 || r==4 % Sets Boundary Conditions for Room Temp
T(r,x,k+1) = 19;
elseif x==2 % Boundary Condition First Node = 27 Celius % Boundary Condition First Node = 27 Celius
T(r,x,k+1) = 27;
elseif x>2 || x==n_x % Middle to End of Material
T(r,x,k+1) = alpha*del_t*(((T(r,x+1,k)-(2*T(r,x,k))+T(r,x-1,k))/L_x^2)+((T(r+1,x,k)-(2*T(r,x,k))+T(r-1,x,k))/L_r^2))+T(r,x,k); %Using finite difference method
end
end
end
t(k) = k+del_t; %Sets time
k = k+del_t;
end
Temp(1:n_r,1:n_x) = T(1:n_r,1:n_x,k);
This is the error that I am receiving
??? Attempted to access T(1,1,2.00525); index must be a positive integer or logical.
Error in ==> Transient2D at 37
T(r,x,k+1) = 19;
3 个评论
per isakson
2014-4-4
Please do not dumb such a lot of poorly formatted and irrelevant code here.
Luke Cartwright
2014-4-4
per isakson
2014-4-4
编辑：per isakson
2014-4-4
everything before k = 1; for a start.
If you want us to run the code say so and provide the code as an attachment.
回答（1 个）
per isakson
2014-4-4
编辑：per isakson
2014-4-4
0 个投票
Use the debug support. It's good. Here are some links on debugging in Matlab
Find out why k is not a whole number.
k = k+del_t; is the prime suspect.
2 个评论
Luke Cartwright
2014-4-4
per isakson
2014-4-4
编辑：per isakson
2014-4-4
Maybe it is not appropriate to use k as an index. You must make sure k is a whole number.
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