Development And Application Of Two-dimensional Shallow Water Numerical Model Considering Turbulence Effect

Flood disaster is one of the most frequent natural disasters in the world.With the development of human society,many floodplains have gradually become densely populated and economically developed areas.Once flood disasters occur in these areas,it will pose a great threat to human property and life safety.In order to reduce the loss of life and property caused by flood disasters,using a reliable flood numerical model to simulate the flood routing process is one of the effective methods for risk assessment and analysis of flood disasters.However,there are two problems in the development and application of two-dimensional shallow water models.On the one hand,most of the existing two-dimensional shallow water models ignore the influence of turbulence terms when simulating the water flow,which can make a difference.On the other hand,most scholars use the two-dimensional shallow water model to simulate the water level and discharge during the flow motion.Meanwhile,there are few reports about the impact on the structure due to water flow using the two-dimensional shallow water model.It is necessary to further study the accuracy and reliability of the impact on the structure due to water flow simulating by the two-dimensional shallow water modelBased on the rectangular grid,a two-dimensional shallow water model considering the turbulence model is developed by using the finite volume method and the central upwind scheme to reveal the flow motion over complicated topography.The main work and conclusions are as follows:(1)Based on the shallow water equation,the parabolic model,the mixed length model and the k-? model are introduced into the two-dimensional shallow water model to develop a two-dimensional shallow water model considering the turbulence model.The model developed in this paper is validated by four open channel flow cases.The simulation results show a great agreement with the experimental results.It indicates that the model develop in this paper can accurately simulate the water level and flow rate information during the flow motion.In addition,comparing the two-dimensional shallow water model without considering the turbulence model,it is found that when the turbulence is significant,considering the turbulence model in the two-dimensional shallow water model can effectively improve the simulation effect of the velocity information,but there is no significant improvement in the water level information.(2)Based on the two-dimensional shallow water model considering the turbulence model developed in this paper,an impact load calculation module is introduced to calculate the impact load on the downstream structure due to flow.The accuracy and stability of the model are verified by two cases of global dam break and partial dam break,and the model is applied to the calculation of urban dense building cases.The simulation results show that the model can accurately simulate the impact load on the downstream structures during the global dam break flow.For the patical dam break case,the simulation results are smooth and cannot simulate the actual water flow turbulence phenomenon.However,it is capable of estimating the maximum impact load on the downstream structures due to partical dam break flow.In addition,the model is used to calculate the impact load on downstream multi-structures due to dam break flow.The simulation results are in accordance with the actual physical phenomenon,which indicates that the model can simulate the impact load in complex situation.