% Heat transfer with convection, heatc1.m
clear                       % variables
format short e              % E format

temp1=70                    % inside temperature
temp4=20                    %outside temperature

kxx = 0.5;                  % thermal conductivity
len = (0.25/12);
hf = [2 10]                 % film coefficient
k12 = hf(1);                % therm cond, length
k23 = kxx / len;
k34 = hf(2);
k22 = k12 + k23;
k33 = k23 + k34
beta = k12*1e7              % zienk factor

stiff = [ k12   -k12      0      0   % stiffness matrix
         -k12    k22    -k23     0
          0     -k23     k33   -k34
          0       0     -k34    k34 ]
df =  [ temp1*beta;  0;   0;  temp4*beta ];   % combined
zienk = stiff;
zienk(1,1)=zienk(1,1)+beta;
zienk(4,4)=zienk(4,4)+beta
format short
temp = inv(zienk) * df;    % displacements
heat = stiff * temp        % force vector

% print the results
fprintf('\n  Heatc1, add convection ')
fprintf('\n  Your name, MENG 421, ')
disp(date)
fprintf('\n  Node  Temp    Heat')
fprintf('\n         F     Btu/Hr\n')

for i = 1:length(df)
  disp(sprintf('  %2.0f %7.2f %7.2f',i,temp(i),heat(i)))
end

%  Heatc1, add convection
%  Your name, MENG 421, 05-Feb-2004

%  Node  Temp    Heat
%         F     Btu/Hr
%   1   70.00   77.92
%   2   31.04    0.00
%   3   27.79    0.00
%   4   20.00  -77.92