24 Computational Modelling in Hydraulic and Coastal Engineering
Maximum tidal flow = 2.0 m 3 /s
Pumping rate = 0, 1.0 m 3 /s and 5.0 m 3 /s
Decay coefficient = 10 –6 s –1
The numerical scheme is given by Equation 2.19. A computational
time step of 300 s has been selected and the calculations terminate
after a pre-determined time period of 2000 time steps.
The tidal effects and the positive impact of pumping to the contaminant concentration as calculated by the numerical simulation are
shown in Figure 2.7.
Computer code 2.3
% Example 2.3 Pollution in a Semi-enclosed Tidal Lagoon
% Qin = Pollutant discharge rate [m^3/s];
% Cin = Pollutant concentration rate at the source [g/m^3];
% Vol = Water volume of the lagoon [m^3];
% Qo = Maximum renewal discharge [m^3/s];
% Qout = Renewal discharge varying with the tide [m^3/s];
% Co = Initial pollutant concentration throughout the lagoon
[g/m^3];
% Rb = Biodegradation rate [1/s];
% Qp = Pump discharge rate [m^3/s];
% Tp = Tidal period [s];
% Dt = Time step [s];
clc; clear all; close all;
% Input data
Qin = 0.1;
Cin = 500;
Vol = 50000;
Inlet
Pumping
discharge
Lagoon
C
Tidal sea
Industrial
discharge
q, c
Q pump
Q tide
Q = Q tide + Q pump + q
Figure 2.6 Water volume exchanges in the lagoon system.