摘要
应用垂向二维非静力假定湍流封闭模式,模拟任意沙波的湍流场以及双向水流作用下沙坡的运动趋势.数值试验结果表明,当沙坡坡度较大时,背水面和沙谷临底层存在明显的水流分离.分离区水平延伸距离为波高的2.7倍,垂向延伸距离为波高的1/3,最大反向流速为43cm/s.而水动压力分量分布的不均匀性是造成水流分离的主要动力机制.通过沙波推移质运移计算分析得出,当双向水流对称时,沙波具有向对称型演变的趋势;而水流非对称时,沙坡将保持原有的非对称形态,同时沿余流向迁移.
This paper deals with the detail of numerical modeling of turbulent flow over arbitrary sand.waves and their developing trends under tidal currents through a vertical two-D model without assumption of hydrostatic pressure. The test results show an obvious flow separation re:gion on the lee slope when the topography becomes steeper, with steepness 2a/ L=1/20 and maximum slope about 28°.The separation region extends 15m downstream, about 2.7 ti.mes of the waveheight, its maximum vertical extent is 2- 5m above the bed, about 1/3 time of the waveheight and the maximum upstream current speed is 43 cm/s. The results also reveal that uneven distribution of hydrodynamic pressure P is the main mechanism causing flow separation on the lee slope. The sandwave developing trends under tidal currents is investigated by relation the caculated bed shear stress and velocity to the bed-load transport rate. It is found that sandwaves would become more symmetric in the areas of equal ebb and flood currents , while in the areas with currents dominated by one tidal stage, sand waves keep the asymmetric shape and advance in the direction of dominant flow.
出处
《海洋通报》
CAS
CSCD
北大核心
1995年第1期29-36,共8页
Marine Science Bulletin
基金
国家自然科学基金课题研究成果之一
关键词
沙波
湍流
推移质
数值模拟
沙波运动
sandwave
turbulent flow
bed-load
numerical modeling
developing trend
