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Spilling or release of foreign particles in the flowing water is considered as pollution of water, and due to the inherent property of water to dissolve the substance, the particulate is well mixed in water. To monitor the extent of pollution in a stream it is essential to know how the pollutants mix in the river. It is observed that vertical mixing of pollutants is a very rapid process in the vertical directions and longitudinal mixing occurs very far from source of pollutant, which is generally out of reach of observations. Thus intermediate or transverse mixing zone is considered very important for water quality modeling. This paper is an attempt to summarize the phenomenon behind pollutant transport, reduction of three-dimensional advection–dispersion equation to two-dimensional equation, and factors causing and affecting transverse mixing of pollutants.

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Submerged vanes are airfoils which are in general placed at certain angle with respect to the flow direction in a channel to induce artificial circulations downstream. By virtue of these artificially generated circulations, submerged vanes were utilized to protect banks of rivers against erosion, to control shifting of rivers, to avoid blocking of lateral intake with sediment deposition, etc. Odgaard and his associates have experimentally obtained the optimum vane sizes and recommended that it can be used for vane design. This paper is an attempt to review and validate the findings of Odgaard and his associates by utilizing computational fluid dynamics and experiments as a tool in which the vane generated vorticity in the downstream was maximized in order to obtain optimum vane parameters for single and multiple vane arrays.

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