Research On Hydraulic Simulation And Visualization Of Unsteady Pipe Network

Pipe network has played an important role nowadays.So simulating the flow of pipe network accurately is significant for both designation and regulation.Free surface flow and pressurized flow are the two phenomenon of pipe flow.Due to the differences of goveming equations,it is difficult to simulate.But with a assumption of a compressible flow in rigid pipe and the definition of compression wave,a model for one-dimensional unsteady flow coupling free surface and pressurised flow is developed to simulate the flow of pipe network.According to the character of pipe network,the model is discreted in a staggered mesh,we define discharge and figure of pipe at the center of the element and define the piezometric head (when pressurised flow) or water level(when free surface flow) at the node.The discrete model is solved with a semi implicit method,which is helpful to obtain a steady result in bigger CFL. Only the nonzero element of coefficient matrix is stored in computing,which can save memory utilization and fit for large-scale computing.The model is demonstrated on examples including water hammer,steady pressurised flow in pipe and free-surface-pressuried flow.Then the model is applied to simulate the Zhujiang River, by comparing the result of simulation with measured data in flood,the ability which model to solve complex shape of cross section is tested.Due to the data size of Computational Fluid Dynamic(CFD) is becoming huge,the analysis, arrangement and processing of the data is difficult.So visualization in scientific computing (VISC) is important for CFD.In this study,VISC software is developed based on the technique of OpenGL for displaying a pipe network.The software builds model of the pipe network in 3D space and fill model with the grads of color in contours.By utilization of the technique of computer graphics,the software realizes dynamic display including zooming,translation motion and free rotation.