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>> solve_ODEs_CA3
Unrecognized function or variable 'Cto'.
Error in solve_ODEs_CA3/ODEs_CA3 (line 37)
CA = Cto*(Fa/Ft) * (To/T);
Error in odearguments (line 90)
f0 = feval(ode,t0,y0,args{:}); % ODE15I sets args{1} to yp0.
Error in ode45 (line 115)
odearguments(FcnHandlesUsed, solver_name, ode, tspan, y0, options, varargin);
Error in solve_ODEs_CA3 (line 4)
[V,y] = ode45(@ODEs_CA3,tspan,y0);
>>
function solve_ODEs_CA3()
tspan = (0:0.01:1);
y0 = [100 0 0 423];
[V,y] = ode45(@ODEs_CA3,tspan,y0);
plot(V,y(:,1),'-o',V,y(:,2),'-o',V,y(:,3),'-o')
title('Temperature Profile');
xlablel('V(dm^3)');
ylabel('t(k)');
legend('F_A','F_B','F_C','T');
function output = ODEs_CA3 (~,y)
Fa = y(1);
Fb = y(2);
Fc = y(3);
T = y(4);
deltaH1 = -20000;
deltaH2 = -60000;
CPA = 90;
CPB = 90;
CPC = 180;
Ua = 4000;
Ta = 373;
ER1 = 4000;
ER2 = 9000;
T0 = 423; %Setting values for first set of variables
%Eq. for K1A and K2A
K1A = 10*exp(ER1*((1/300)-(1/T)));
K2A = 0.09*exp(ER2*((1/300)-(1/T)));
%Eq. for FT
Ft = Fa + Fb + Fc;
%Eq. for CA, CB, CC
CA = Cto*(Fa/Ft) * (To/T);
CB = Cto*(Fb/Ft)*(To/T);
CC = Cto*(Fc/Ft)*(To/T);
%Eq. for RA1 and RA2
RA1 = -K1A*CA;
RA2 = -K2A*(CA)^2;
%Eq. for dFa, DFb, and Dfc derivatives
dFAdV = RA1 +RA2;
dFBdV = -RA1;
dFCdv = -(1/2)*(-RA2);
%Derivative of dT eq.
dTdV = (Ua*(Ta-T)+(-RA1)*(deltaH1)+(-RA2)*(-deltaH2))/((Fa*CPA)+(Fb*CPB)+(Fc+CPC));
ouput = [dFAdV;dFBdV:dFCdV;dTdV];
size(output)
end
end
回答（1 个）
Cris LaPierre
2020-10-2
0 个投票
Your equations for CA, CB, CC in ODEs_CA3 function use a variable Cto that has not been created or at least does not exist within the scope of that function. You either need to define it, or pass it in as input to the function.
7 个评论
Abby Revoir
2020-10-2
编辑：Abby Revoir
2020-10-2
Cris LaPierre
2020-10-2
编辑：Cris LaPierre
2020-10-2
[t,y] = ode45(odefun,tspan,y0)
It looks like your are using [V,y] = ode45(@(V,C)ODEs_CA3(tspan,y0));
Try this instead:
[V,y] = ode45(@ODEs_CA3,tspan,y0);
There are several other typos in your code, but once you fix those, your code runs and produces a figure (I had to make up a value for Cto so the code would run).
Abby Revoir
2020-10-2
Steven Lord
2020-10-2
You define a variable dFCdv but then try to use a variable dFCdV. Lower-case v and upper-case V are not interchangeable.
dFCdv = -(1/2)*(-RA2);
ouput = [dFAdV:dFBdV:dFCdV:dTdV];
You also don't want to use the colon operator : here, you want to separate the variables with semicolons ;.
Abby Revoir
2020-10-2
Cris LaPierre
2020-10-2
Use semicolons to create your output variable.
output = [dFAdV;dFBdV;dFCdV;dTdV];
Abby Revoir
2020-10-2
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