Warning

This documentation is for an old version of Cantera. You can find docs for newer versions here.

ignite.m

function plotdata = ignite(g)
% IGNITE Zero-dimensional kinetics: adiabatic, constant pressure.
% 
%    This example solves the same problem as 'reactor1,' but does
%    it using on of MATLAB's ODE integrators, rather than using the
%    Cantera Reactor class.
%

help ignite

if nargin == 1
   gas = g;
else
   gas = IdealGasMix('gri30.xml');
end

nsp = nSpecies(gas);

% set the initial conditions

set(gas,'T',1001.0,'P',oneatm,'X','H2:2,O2:1,N2:4');

y0 = [intEnergy_mass(gas)
      1.0/density(gas)
      massFractions(gas)];

time_interval = [0 0.001];
options = odeset('RelTol',1.e-5,'AbsTol',1.e-12,'Stats','on');

t0 = cputime;
out = ode15s(@reactor_ode,time_interval,y0,options,gas,@vdot,@area,@heatflux);
disp(['CPU time = ' num2str(cputime - t0)]);

plotdata = output(out,gas);

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% the functions below may be defined arbitrarily to set the reactor
% boundary conditions - the rate of change of volume, the heat
% flux, and the area.


% Rate of change of volume. Any arbirtrary function may be implemented.
% Input arguments: 
%   t      time
%   vol    volume
%   gas    ideal gas object

function v = vdot(t, vol, gas)
%v = 0.0;                                 %uncomment for constant volume
v = 1.e11 * (pressure(gas) - 101325.0);   % holds pressure very
                                          % close to 1 atm

% heat flux (W/m^2). 
function q = heatflux(t, gas)
q = 0.0;                                  % adiabatic


% surface area (m^2). Used only to compute heat transfer.
function a = area(t,vol)
a = 1.0;

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% Since the solution variables used by the 'reactor' function are
% not necessarily those desired for output, this function is called
% after the integration is complete to generate the desired
% outputs. 

function pv = output(s, gas)
times = s.x;
soln = s.y;
[m n] = size(times);
pv = zeros(nSpecies(gas) + 4, n);

set(gas,'T',1001.0,'P',oneatm);

for j = 1:n
  ss = soln(:,j);
  y = ss(3:end);
  mass = sum(y);
  u_mass = ss(1)/mass;
  v_mass = ss(2)/mass;
  setMassFractions(gas, y);
  setState_UV(gas, [u_mass v_mass]);
  
  pv(1,j) = times(j);
  pv(2,j) = temperature(gas);
  pv(3,j) = density(gas);
  pv(4,j) = pressure(gas);
  pv(5:end,j) = y;
end

% plot the temperature and OH mass fractions.
figure(1);
plot(pv(1,:),pv(2,:));
xlabel('time');
ylabel('Temperature');
title(['Final T = ' num2str(pv(2,end)) ' K']);

figure(2);
ioh = speciesIndex(gas,'OH');
plot(pv(1,:),pv(4+ioh,:));
xlabel('time');
ylabel('Mass Fraction');
title('OH Mass Fraction');