Abstract: Research on warm water and pollutant diffusion is of great significance to the health of river ecosystem. The convection and diffusion of warm water and pollutants in the adjacent of drainage outlet are strongly three-dimensional. In this research, a mathematical model of temperature and concentration field is developed based on 3-D turbulent flow hydrodynamic model. In the modeling, porosity is used to deal with irregular boundary, and VOF method is used to simulate free surface. In addition, the turbulent model and the Wall Function are used in the modeling. This model is applied to simulate water level, flow field, turbulent kinetic energy and its dissipation rate, and diffusion regularity of temperature and concentration field around the drainage outlet. This model could well simulate the stratification of concentration and temperature in vertical direction.

Key words: mathematical model, 3-D turbulent flow, temperature field, concentration field, turbulent model, wall function