Ordinary differential equations 25
Qo = 2;
Co = 1;
Rb = 0.000001;
Qp0 = 0;
Qp1 = 1;
Qp5 = 5;
Tp = 43200;
Dt = 300;
C0 = Co;
C1 = Co;
C5 = Co;
% Main program;
for n = 1:2000;
t= n*Dt;
% Different outflow pumping rates;
Qout0 = Qo*abs(cos((2*pi/Tp)*t))+Qp0;
Qout1 = Qo*abs(cos((2*pi/Tp)*t))+Qp1;
Qout5 = Qo*abs(cos((2*pi/Tp)*t))+Qp5;
% Calculation of the contaminant concentrations;
Cnew0 = C0 + (Cin*Dt*Qin/Vol) - (C0*Dt*Qout0/Vol)
- (Rb*Dt*C0);
Cnew1 = C1 + (Cin*Dt*Qin/Vol) - (C1*Dt*Qout1/Vol)
- (Rb*Dt*C1);
Cnew5 = C5 + (Cin*Dt*Qin/Vol) - (C5*Dt*Qout5/Vol)
- (Rb*Dt*C5);
45
40
35
30
25
20
15
10
5
0 0
200 400 600 800 1000 1200 1400 1600 1800 2000
Number of time steps
Contaminant concentration (g/m 3
)
No pumping
Pumping rate 1 m 3 /s
Pumping rate 5 m 3 /s
Figure 2.7 Pumping effects on contaminant concentration within the lagoon.