Hydrodynamics of the Semi-Immersed Cylinder by Forced Oscillation Model Testing

In this paper, the hydrodynamic coefficients of a horizontal semi-immersed cylinder in steady current and oscillatory flow combining with constant current are obtained via forced oscillation experiments in a towing tank. Three nondimensional parameters(Re, KC and Fr) are introduced to investigate their effects on the hydrodynamic coefficients.The experimental results show that overtopping is evident and dominates when the Reynolds number exceeds 5×105 in the experiment. Under steady current condition, overtopping increases the drag coefficient significantly at high Reynolds numbers. Under oscillatory flow with constant current condition, the added mass coefficient can even reach a maximum value about 3.5 due to overtopping while the influence of overtopping on the drag coefficient is minor.

凤河和龙河的历史渊源及对廊坊文化特征的影响

廊坊的区域文化特征深受凤河和龙河的影响。凤河和龙河均属永定河水系,凤河在金朝开始出现,元明时期又有改道,明末清初时正式定名;龙河出现并定名于清朝初年。在历史发展的长河中,凤河和龙河以独特的地理特征、历史文化和风俗传说,深刻影响到廊坊的历史文化发展。彰往察来,研究凤河、龙河对于廊坊地域文化的影响,对于廊坊今后的文化定位和文化建设乃至京津冀协同发展均具有重要的意义。