Virtual Basin Technology And Its Application In Digital Lake Engineering

With the constant improvement of the hydraulic engineering construction and the management of basin water resources in many countries in the world, basin-water-resource-management decision support system (BWRM-DSS) is developing towards the direction of intelligent and visualization. The principle of the BWRM-DSS is the multi-knowledge crossed research realm which involves the system engineering, hydrodynamic, virtual reality, spatial information science and computer technology. By effective integration of engineering data, business models, GIS (Geographic Information System) information and visual high-dimensional information, BWRM-DSS can intuitive visualize the results of scientific computation, and can fully reveal hydrodynamic response mechanism under the different conditions. Furthmore, it is able to provide efficient decision-making for BWRM and hydraulic engineering construction. Fluid simulation plays an important role in BWRM-DSS based on virtual basin, because realistic fluid can enhance the realism of virtual simulation and can demonstrate dynamically the flow regime features of water flow such as the scope of flood, water level, water depth, flow velocity, by coupling with some mathematical model. However, physically-based fluid simulation possesses the characteristics of high dimension, nonlinear, and its computational complexity increases with geometric series. So, how to build an efficiently computing framework in virtual basin simulation, full excavate computing resources and implement parallel computing mixing software and hardware, has become a urgent scientific problem needed to be solved and a technology bottleneck in virtual basin simulation. On the other hand basin-water-resources system is a complex system under the effect on many aspects. The decision-making process of basin-water-resources management involved multiple areas, e.g. social, economic, hydrological, water flowing, hydraulic and ecological, with vast amounts of heterogeneous data and many models such as meteorological, hydrology, flood, evaluation. Hence, Building a digital platform based on virtual basin simulation, which is easy to extend and integrate, has important scientific significance and practical value to achieve optimal allocation of water resources and provide decision support for the construction and management of water conservancy.Focusing on the efficient solving problem of virtual basin simulation based on parallel computing mixing software and hardware and its application in hydraulic engineering, under the support of the-973-project and the-Dong-Lake-project, this thesis proposes the construction principle and method of the digital platform of virtual basin simulation, after fully research the principle of fluid simulation, the parallel computing method of hybrid software-hardware, and the implementing framework of platform. Finally, a virtual basin digital platform based on fluid simulation is developed and multi-dimensional information of large lake and ocean are visualized. Besides, the research results are used in practical hydraulic engineering to provide efficient theory and technology support for related personnel. The main work and innovation are as follows:(1)To solve the problem of time consumption of physically-based fluid simulation, an improved algorithm of the nearest neighbor particles search coupling the coherent of time and space for Smoothed Particle Hydrodynamics (SPH) is proposed after the principle of physically-based fluid simulation and SPH method are discussed. Moreover, a real-time and efficient fluid simulation is implemented based on the proposed algorithm and CUDA architecture.(2) Focusing on the characteristic which the physically-based fluid is not suited for large scale fluid or large scope fluid, a river simulation for large scale terrain and complex river network is presented. In the proposed method, Bezier curves and streaming normal maps are used to simulate the flow of water through rivers and multiple quadratic Bezier curve segments are linked together to create complex river curves and junctions. Because of rendering the Bezier curves with bounding quads using only four vertices per curve, it has high rendering performance and can meet real-time simulation requirement of large scale river with complex river network.(3) For large-scale lake and ocean simulation, the classical spectral model is adopted to implement lake and ocean simulation considering the influence of wind direction, wind speed and others factors for the forms of waves based on CUDA. Meanwhile, focusing on the problems that system integration of common simulation system is not high and the development time is too long, a quick developing method of a three-dimensional digital lake is proposed combining OSG and the spectral model by employing C++/CLI technology. Moreover, the research results are used in practical hydraulic engineering. According to the feature of lake water surface, we give another lake simulation method utilizing project grid and Perlin noise, and developed a prototype system with realistic effect based on CUDA.(4) Combining the distributed lake flow model and water quality model, the three-dimensional simulation of the wind-driven current and pollution diffusion in lake are realized, respectively, on the basis of the three-dimensional digital lake based on COSG (C++/CLI and OSG). Facing with the requirements of basin simulation and BWRM-DSS, a loosely-coupled and model-driven system framework (LCMD framework) is proposed. Based on LCMD framework, a synthetically digital platform integrating a BWRM-DSS with a three-dimensional digital lake system based on C++/CLI and OSG is developed, and put into use in Dong-lakes-project in Wuhan city.(5) A three-dimensional flood routing visualization method is put forward to solve the problem of virtual basin simulation in large scale and large terrain using real-time physically-based fluid. The presented method utilizes the group animation in GIS and the hydrodynamic model. Finally, it had been integrated into the-973-project by adopting continued integrated loosely-coupled technology.