Rivers are the main source of water supply. At present, water purification methods are still not sufficiently effective, especially in cases of emergency emissions of various substances. In connection with the assessment of the state of the aquatic environment, the methods of describing the distribution of contaminants in water bodies are of interest. This article presents a mathematical model of the process of heat and mass transfer, velocity fields, temperature and concentration of polluting components in a certain section of the river. The developed methods for predicting the levels of distribution of contaminants entering the aquatic environment can be used to control the quality of river water, including subject to accidental release of various substances into the reservoir. Pollutants can enter the water from the catchment area, with sewage, as well as a result of emergency salvo emissions from accidental breaks in oil pipelines. Contaminants can either be dissolved in water and then spread downstream, or transported in the form of suspended particles under the influence of the flow of a river. The latter in some cases may sink to the bottom of the river and then rise from the bottom, for example, under adverse weather conditions, when the flow characteristics change. As a result of the analysis of existing models of pollution of the aquatic environment, a mathematical model based on solving equations for turbulent diffusion was constructed within the framework of continuum mechanics. This takes into account the configuration and depth of the river, its flow rate, ambient temperature, parameters of emission sources (coordinates, dynamics and composition of emissions). With this approach, it is possible to include additional factors that need to be taken into account when calculating environmental pollution. Using the laws of continuum mechanics, a boundary-value problem has been posed to describe the heat and mass transfer of pollutants in a river. The paper deals with the spatial problems of convective heat and mass transfer of pollutants in a river. The source of pollution is modeled by a surface source of mass of heated substances released as a result of a volley release for some time. It is believed that the flow has a developed turbulent character, and to describe convective transfer under the influence of a river flow, the three-dimensional Reynolds equations for a turbulent flow are used. This problem was solved numerically. Discrete analogue was obtained on the basis of the finite volume method. The system of algebraic equations obtained as a result of discretization was resolved using the SIP method. To define the configuration of the river, the method of fictitious areas was used; in the control volumes of the computational domain, outside the river, the initial values of the functions were specified and did not change in the course of the calculations, and the velocity components were set equal to zero. As a result of numerical calculations, spatial distributions of the fields of velocity, temperature, and concentrations of the components of contaminants at different times were obtained. Using the mathematical model presented in this paper, we can study the dynamics and spatial pattern of water pollution under the influence of various external conditions (water temperature, river flow rate, etc.), as well as the parameters of the source of pollution.
|Affiliation of speaker||Tomsk Polytechnic University|
|Publication||Journal of Cleaner Production|
|Position of speaker||professor|