采用任意拉格朗日-欧拉(Arbitrary La grangian-Eulerian,ALE)描述法,推导了二维流变区域不可压流体流动的控制方程。基于刚性断面边界特点,简化得到了薄平板强迫振动绕流场控制方程,采用有限差分法开展了薄平板大幅强迫扭转振动的CFD...采用任意拉格朗日-欧拉(Arbitrary La grangian-Eulerian,ALE)描述法,推导了二维流变区域不可压流体流动的控制方程。基于刚性断面边界特点,简化得到了薄平板强迫振动绕流场控制方程,采用有限差分法开展了薄平板大幅强迫扭转振动的CFD模拟。研究发现,薄平板小幅扭转振动气动力呈线性特性,但大幅扭转振动气动力非线性显著,且气动力非线性随来流折算风速的增大而变得显著。从一个周期内气流做功来看,虽然大幅扭转振动时薄平板转动轴到后缘是耗散气流能量的气动稳定区,但当折算风速较高后,上游侧的半个薄平板表面变为气动不稳定区,此时气流对整个薄平板所作总功由负变为正,薄平板将从气流中吸收能量。研究认为,当折算风速较高时,大幅扭转振动的薄平板将进入气动不稳定状态。展开更多
In order to predict the local scour hole and its evaluation around a cylindrical bridge pier, the computational fluid dynamics （CFD） and theories of sediment movement and transport were employed to carry out numeric...In order to predict the local scour hole and its evaluation around a cylindrical bridge pier, the computational fluid dynamics （CFD） and theories of sediment movement and transport were employed to carry out numerical simulations. In the numerical method, the time-averaged Reynolds Navier-Stokes equations and the standard k-e model were first used to simulate the three-dimensional flow field around a bridge pier fixed on river bed. The transient shear stress on river bed was treated as a crucial hydrodynamic mechanism when handling sediment incipience and transport. Then, river-bed volumetric sediment transport was calculated, followed by the modification of the river bed altitude and configuration. Boundary adaptive mesh technique was employed to modify the grid system with changed river-bed boundary. The evolution of local scour around a cylindrical bridge pier was presented. The numerical results represent the flow pattern and mechanism during the pier scouring, with a good prediction of the maximum scour hole depth compared with test results.展开更多
文摘采用任意拉格朗日-欧拉(Arbitrary La grangian-Eulerian,ALE)描述法,推导了二维流变区域不可压流体流动的控制方程。基于刚性断面边界特点,简化得到了薄平板强迫振动绕流场控制方程,采用有限差分法开展了薄平板大幅强迫扭转振动的CFD模拟。研究发现,薄平板小幅扭转振动气动力呈线性特性,但大幅扭转振动气动力非线性显著,且气动力非线性随来流折算风速的增大而变得显著。从一个周期内气流做功来看,虽然大幅扭转振动时薄平板转动轴到后缘是耗散气流能量的气动稳定区,但当折算风速较高后,上游侧的半个薄平板表面变为气动不稳定区,此时气流对整个薄平板所作总功由负变为正,薄平板将从气流中吸收能量。研究认为,当折算风速较高时,大幅扭转振动的薄平板将进入气动不稳定状态。
基金Project(50978095) supported by the National Natural Science Foundation of ChinaProject(IRT0917) supported by the Program for Changjiang Scholars and Innovative Research Team in Chinese UniversityProject supported by China Scholarship Council
文摘In order to predict the local scour hole and its evaluation around a cylindrical bridge pier, the computational fluid dynamics （CFD） and theories of sediment movement and transport were employed to carry out numerical simulations. In the numerical method, the time-averaged Reynolds Navier-Stokes equations and the standard k-e model were first used to simulate the three-dimensional flow field around a bridge pier fixed on river bed. The transient shear stress on river bed was treated as a crucial hydrodynamic mechanism when handling sediment incipience and transport. Then, river-bed volumetric sediment transport was calculated, followed by the modification of the river bed altitude and configuration. Boundary adaptive mesh technique was employed to modify the grid system with changed river-bed boundary. The evolution of local scour around a cylindrical bridge pier was presented. The numerical results represent the flow pattern and mechanism during the pier scouring, with a good prediction of the maximum scour hole depth compared with test results.
