海洋底边界层中实测海流的垂直分布I.余流边界层

VERTICAL DISTRIBUTION OF OCEAN CURRENTS IN THE BOTTOM BOUNDARY LAYER OF SHELF SEAS PART I. BOTTOM BOUNDARY LAYER OF RESIDUAL CURRENTS

海底以上 1— 2m水层的海流垂直分布和变化 ,对于海底泥沙运动和海洋工程设计具有十分重要的意义。迄今为止 ,研究者分别从实测资料、实验室实验和理论等方面对底边界层中稳定流动的垂直分布进行了研究 ,其结果均难以直接满足工程需要。本文基于现有的理论和实验结果 ,发展了现有海底边界层理论 ,运用把稳定流的底Ekman层与对数层相配匹的方法确定了实测余流的垂直分布 ,并给出了在渤海石油平台区的应用实例。结果表明 ,本文给出的原理和方法在应用中与实测结果符合良好 。

In the maritime civil engineering and in particular the placement of such engineering structures on bed as cables and pipelines, oil and gas platforms, jetties and breakwaters, it is essential to understand the vertical distribution of bottom currents and their variations at the engineering site. In the stationary theory, the boundary layer is divided into two regions, a logarithmic layer overlain by a thicker, turbulent Ekman layer. A third region, the laminar sublayer, may exist immediately above the bottom, provided that the bottom is hydrodynamically smooth. Practically, it is difficult to meet the needs of the placement of engineering structure on the bed if the vertical distribution of the bottom current within the 1-2m layer above bed was obtained from the current meter records at a few levels. This paper studies how the Ekman layer links the logarithmic layer using the residual current data obtained from Station AA of the Bohai Sea. Some typical values at this station were found as follows: E = 2.06m, L = 0.66m, * = -0.056m/s * = 0.030cm/s, z 0 = 0.33cm where E is the thickness of the bottom Ekman layer for the residual current; δ L , the thickness of the logarithmic layer, ( * , * ), the east and north components of friction velocity and z 0 , roughness length.