Numerical Simulation Of Flow Characteristic At 90-Degree Open-Channel Junction

Open-channel junction flow often occurs in hydraulic engineering. Itgenerates theoretical and practice interest for urban flood control, bed erosion,sediment transport and pollutant transport. Detailed hydrodynamics ofjunction flow is found to be complex and there exists two kinds of factors thatcharacterize the flow physics: geometry character and flow character. Theformer includes the size, shape, slope and angle between the two combiningchannels, and the latter includes the flow Reynolds number, channelroughness, discharge ratio, and fluid properties. So many variables make itdifficult to solve the problem through experimental studies. Numericalsimulation can fit the variable boundaries flexibly. With the development ofcomputational fluid dynamics, Numerical Simulation evolves as the primaryway for solving the open-channel junction flow.In this thesis, the depth-averaged equations combined with the explicitalgebraic stress turbulence model were applied to the simulation of 90oopen-channel junction with horizontal slope. The governing equations werediscretized on staggered grids by finite volume method. SIMPLE algorithmwas used to complete the velocity-pressure correction. The algebraicequations were solved by TDMA method. Computation was performed forfour different flow conditions. The numerical results were compared with theexperiment data. It showed good agreements for the separation zone and watersurface elevation simulation.In addition, three-dimensional equations coupled with the explicitalgebraic stress turbulence model were also applied to the model. The solutionprocedure was similar with that in the depth-averaged equations. The resultsshowed advantageous results for the separation zone and water surfaceelevation simulation. Furthermore, secondary flow phenomena in the crosssection downstream the junction were found owning to the use of the explicitalgebraic stress turbulence model.The numerical model applied in the paper can be employed to morecomplex problem occurred in the engineering, it also can work as a foundationto study bed erosion, sediment transport and pollutant transport.