Shape of boundary transition section for mountains-gorge bridge site terrain model

To study the appropriate boundary transition section shape of terrain model for mountainsgorge bridge site, a kind of transition section curves was derived based on the theory of flow around cylinder with ideal fluid. According to the different shapes of the curve transition section with equivalent slope of 058 and the ramp transition section with included angle of 30°, an ideal two-dimensional platform terrain was used as the analysis model to comparatively analyze the flow separation behavior and the distribution characteristics of average wind field after airflow flowed along the two transition sections by CFD commercial software FLUENT. Furthermore, the total flow transition lengths of different curve transition section shapes were also compared. The results show that when airflow flows along the curve transition section with equivalent slope of 0.58, the distribution characteristics of wind velocity field after airflow flowed along it are much closer to the distribution characteristics of reference wind velocity field than those when airflow flows along the ramp transition section with included angle of 30°, and its total flow transition length is also the relative shortest. The research conclusions could provide some references for the complex terrain model studies on wind characteristics over the mountainsgorge bridge site by wind tunnel test and CFD methods.