Dispersion of fine settling particles from an elevated source in an oscillatory turbulent flow |
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| Affiliation: | 1. State Key Laboratory for Turbulence and Complex Systems, College of Engineering, Peking University, Beijing 100871, China;2. NAAM Group, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia;1. Key Laboratory of State Forestry Administration on Soil and Water Conservation, School of Soil & Water Conservation, Beijing Forestry University, Beijing 100083, China;2. College of Engineering, Peking University, Beijing 100871, China;1. Key Laboratory of State Forestry Administration on Soil and Water Conservation, School of Soil and Water Conservation, Beijing Forestry University, Beijing 100083, China;2. Beijing Engineering Research Center of Soil and Water Conservation, Beijing Forestry University, Beijing 100083, China;3. College of Engineering, Peking University, Beijing 100871, China;1. School of Soil and Water Conservation, Beijing Forestry University, Beijing 100083, China;2. Key Laboratory of State Forestry Administration on Soil and Water Conservation, Beijing Forestry University, Beijing 100083, China;3. State Key Laboratory of Turbulence and Complex Systems, College of Engineering, Peking University, Beijing 100871, China;1. State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, China Institute of Water Resources and Hydropower Research, Beijing 100038, China;2. College of Shipbuilding Engineering, Harbin Engineering University, Harbin, Heilongjiang 150001, China;3. Key Laboratory of State Forestry Administration on Soil & Water Conservation, School of Soil & Water Conservation, Beijing Forestry University, Beijing 100083, China;1. State Key Laboratory of Hydroscience and Engineering; Department of Hydraulic Engineering, Tsinghua University, Beijing 100084, China;2. State Key Laboratory for Turbulence and Complex Systems, College of Engineering, Peking University, Beijing 100871, China;3. NAAM Group, King Abdulaziz University, Jeddah, Saudi Arabia |
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| Abstract: | The present paper examines the stream-wise dispersion of suspended fine particles with settling velocities in an oscillatory turbulent shear flow with or without a non-zero mean over a rough-bed surface when the particles are being released from an elevated continuous source. A finite-difference implicit method is employed to solve the unsteady turbulent convective-diffusion equation. A combined scheme of central and four-point upwind differences is used to solve the steady state equation and the Alternating Direction Implicit (ADI) method is adopted for unsteady equation. It is shown how the mixing of settling particles is influenced by the tidal oscillatory current and the corresponding eddy diffusivity when the initial distribution of concentration regarded as a line-source. The vertical concentration profiles of suspended fine particles with settling velocities are presented for different downstream stations for various values of settling velocity and the frequency of the oscillation in tidal flow. For two-dimensional unsteady dispersion equation, the behaviour of iso-concentration lines for different values of settling velocity, frequency of the oscillation, dispersion time and releasing height is studied in terms of the relative importance of convection and eddy diffusion. |
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