Numerical simulation method for overflow flow of a windward conservation type riverway

Abstract

The invention discloses a numerical simulation method for overflow flow of a windward conservation type riverway. In order to give full play to the advantages of high calculation efficiency of the one-dimensional model and high calculation precision of the two-dimensional model, the water flow in the river channel is simulated by adopting the one-dimensional model, and the river channel is simulated by adopting the two-dimensional mathematical model after overflowing. The one-dimensional model and the two-dimensional model both adopt a central format finite volume method to discretely conservea shallow water equation set. The interface flux is calculated by adopting a windward conservation type Godunov numerical calculation format, and the model has very good numerical conservation characteristics and wide adaptability, and can be used in large river areas of great rivers and also can be used in medium and small river areas. The characteristic invariant theory with strict physical mathematical significance is adopted to calculate the water flow interaction process inside and outside the river channel, the processing method can overcome the defect that a weir flow formula is adopted in a traditional method to carry out water flow interaction calculation, the precision of water flow interaction calculation between the one-dimensional model and the two-dimensional model is improved, and the overall quality conservation characteristic of the mathematical model is guaranteed.

Description

technical field [0001] The invention relates to the field of water conservancy engineering, in particular to the field of flood control and disaster reduction, in particular to a numerical simulation method for windward-conserving river channel overflow. Background technique [0002] With changes in global climate patterns, extreme heavy rainfall events occur frequently, and rivers often overflow beyond the standard. After flooding, the residents in the submerged area will cause serious loss of life and property. As a useful tool, the mathematical model can simulate the process of river flood overflow and provide valuable decision-making information for flood control decision-making departments. The one-dimensional mathematical model has high calculation efficiency and can provide good calculation results in the simulation of river flow. However, once the flood overflows, the water flow outside the river presents obvious two-dimensional movement characteristics. At this time...

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Problems solved by technology

[0003] At present, the coupling method of one-dimensional and two-dimensional models commonly used in engineering is to use the form of weir flow formula to calculate the interaction of water flow inside and outside the channel. However, this method cannot express the momentum exchange between one-dimensional and two-dimensional models. There are great uncertainties in the selection of coefficients, which bring some errors to the simulation of flood overflow and directly affect the accuracy of the flood inundation range and inundation process

In addition, the numerical discrete schemes without shock wave capture ability that are often used in current engineering, such as the Preissmann scheme commonly used in river channel simulation, often cannot obtain correct calculation results under the conditions of steep terrain and complex flow regimes. The application effect is good in the water flow simulation of large rivers and large rivers, but it often fails when used in the simulation of overflow flood process of small and medium rivers

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