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% Tank parameters
A1 = 30;    % First tank cross-sectional area [m²]
r1 = 1.2;   % First tank time constant [s/m²]
A2 = 50;    % Second tank cross-sectional area [m²]
r2 = 0.7;   % Second tank time constant [s/m²]
Fin0 = 9.4; % Initial inlet flow rate [m³/s]
h1_0=11.28;
h2_0=6.58;
opts = odeset('RelTol',1e-9,'AbsTol',1e-12);
function df = noninteractingtanks(t, y)
A1 = 30;    % First tank cross-sectional area [m²]
r1 = 1.2;   % First tank time constant [s/m²]
A2 = 50;    % Second tank cross-sectional area [m²]
r2 = 0.7;   % Second tank time constant [s/m²]
Fin0 = 9.4; % Initial inlet flow rate [m³/s]
h1_0=11.28;
h2_0=6.58;
h1=y(1);
h2=y(2);
dh1dt=(Fin0-h1/r1)/A1;
dh2dt=(h1/r1-h2/r2)/A2;
df=[dh1dt; dh2dt];
end
y0=[h1_0; h2_0];
tspan=[0 3600];
[t,y]=ode45(@noninteractingtanks, tspan, y0, opts);
sol_nonint=[y(end,1); y(end,2)];
figure(1);
plot(t,y(:,1), 'b-', 'LineWidth', 1.5);
grid on;
xlabel('Tempo(s)');
ylabel('h1(t)');
title('noninteractingtanks_1')
figure(2);
plot(t,y(:,2), 'r-', 'LineWidth', 1.5);
grid on;
xlabel('Tempo(s)');
ylabel('h2(t)');
title('noninteractingtanks_2');