Gravity currents are flows driven by the density differences. The density differences behind such flows may arise from containing the different compositions in fluids. Knowledge of gravity currents is important in the prediction of sedimentation in reservoir, in the field of hydraulics, which controls the transport of sediments depending on the man-made submarine facilities. Recent years, it appears to be facing serious challenges of siltation problems, resulting from short bursts of heavy rainfall caused by the global climate change. To maintain the sustainable water resources in reservoir, the development of such measures to control sedimentation is a big issue in engineering, accompanied with the purposes to stop, dilute or divert the flow motion. The way can be done by a solid or permeable obstacle placed in front of intakes or bottom outlets in our thinking. To enhance the efficiency of de-siltation, this study goes further to make some recommendations towards minimization of reservoir siltation to a manageable extent through numerical simulations. In the literature, most attention focused on the evolution of gravity currents on the horizontal boundary only, which is channelized and confined to flow between parallel walls, i.e. the lock-exchange system. Little is known about the currents interact with the changeable bottom boundary in this system. For this point, in this study, the high-resolution simulation is used to investigate the flow morphology of gravity currents over different topography, including the horizontal plane, the inclined bottom and the embedded obstacles. The evolution of gravity currents and their localized dynamic behavior are mainly concerned, investigated by the Navier-Stokes equations based on the large-eddy simulations. Both the quantitative observation and qualitative analysis are involved, including the concentration distributions, energy budgets, force responses etc.

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Key words: Gravity currents, Flow morphology, Large eddy simulations, Navier-Stokes equations