MATLAB: How to integrate a set of ODEs given that the initial conditions also change (linearly) within the concerned time span

chemical engineeringode

Best Answer

function driver
tstart = 0.0;
tend = 1.0;
flag = 1;
[T1 Y1] =ode45(@(t,y)myfun(t,y,flag),[tstart tend],[0.01;600]);
tstart = 1.0;
tend = 2.0;
flag = 2 ;
[T2 Y2] = ode45(@(t,y)myfun(t,y,flag),[tstart tend],[Y1(end,1);Y1(end,2)]);
tstart = 2.0;
tend = 10.0;
flag = 3 ;
[T3 Y3] = ode45(@(t,y)myfun(t,y,flag),[tstart tend],[Y2(end,1);Y2(end,2)]);
function myfun(t,y,flag) 
if flag==1 
  yin = 0.01;
  Tin = 600;
elseif flag==2
  yin = 0.01+(t-1)*0.02;
  Tin = 600+(t-1)*100;
elseif flag==3
  yin = 0.03;
  Tin = 700;
end 
...
Best wishes
Torsten.
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