Numerical Study of a Combined Fluid Flow and Pollutant Concentration Dispersion in a Confluent River and Canal

Abstract

The problems of air pollution and of water pollution are serious and harmful to human beings and other living organisms as contaminated water and pollution can affect human life, aquatic organisms and fisheries. Besides polluted water has long been recognized as an indirect cause of foul odors. This study investigates concentrations and dispersion of toxic pollutants released into a river and a canal. A model is simulated from the real geography of Thailand. Our study involves analyzing and calculating the continuity equation, momentum equations and species concentration dispersion equation based on the finite element method (FEM). This research focuses on the effects of inlet velocities on the concentration dispersions. The Reynold number of inlet velocities in the canal are 8.3 × 104, 1.2 × 105 and 1.7 × 105, and the Reynold number of inlet velocities in the river are 2.15 × 105, 4.3 × 105 and 8.6 × 105. Generally, the velocity of the canal increases when the inlet velocities of the river increases. Also, river velocity generally increases when the inlet velocities in the canal increase. Therefore, high flow velocity has a major impact on enhanced speed, elevated pollutant concentrations. Meanwhile concentrations of toxic substances can be reduced rapidly. In certain cases, the flow velocities in canals and rivers are very low, resulting in higher average concentrations. Moreover, flow velocities can cause collisions at the confluence, resulting in high concentrations of toxic substances and increased average pollutant concentrations. The research findings should be further developed and applied to other types of models or similar issues for effective pollution control and management.