Numerical investigation of pollution transport around a single non-submerged spur dike

Abstract

Industrial contaminants and chemicals adversely impact surface water quality and may lead to serious health risks to human and ecosystems. Rivers as one of the major surface water resources receive wastewaters and transport dissolved pollutions in water through Advection-Dispersion processes. A minimum distance known as the mixing length is required for complete mixing and dispersion of the pollutants. Since the concentration of pollutants often exceeds the self-purification capacity of rivers within this distance, reducing it decreases the negative impacts on the aquatic ecosystems. Creating turbulent flows with inherent mixing characteristics is an efficient measure in decreasing the mixing length. Spur dikes that are widely used in river engineering are able to reduce the mixing length by virtue of the turbulence made in a stream. Given the fact that entry of pollutants into the surface water is inevitable and the influence of spur dikes on the characteristics of pollution transport has not been meticulously investigated, this study aimed at the numerical simulation of pollution transport in a rectangular channel adjacent to a spur dike. We thus invoked Flow-3D to simulate flow and transport characteristics around an impermeable and non-submerged rectangular spur dike. The findings of this study enhance our understanding of spur dike effects on pollution transport. Notwithstanding the fact that the spur dike effectively decreased the mixing length of the pollution, the location of the pollutant entry also played a prominent role in reducing the length of this region.