夜间稳定边界层中小尺度地形激发的形式阻力和波动阻力   总被引：1，自引：0，他引：1       下载免费PDF全文

姜瑜君  桑建国  刘辉志  刘树华 《地球物理学报》2007,50(1):43-50

通过求解含有摩擦耗散的线性化大气动力学方程组,得到了在夜间稳定大气边界层中小尺度地形产生的波动阻力和形式阻力的解析解.结果表明边界层中的稳定度、风速和湍流状态、边界层厚度、上部残余层中的稳定度和风速以及地形高度和坡度,都会影响波动阻力和形式阻力的大小,应在数值模式的参数化方案中给予考虑.分析还表明,当地形坡度减到一定程度时,形式阻力可以忽略不计.  相似文献   

An extended time-dependent numerical model of the mild-slope equation with weakly nonlinear amplitude dispersion     

ZHAO Hongjun  SONG Zhiyao  XU Fumin  LI Ruijie 《海洋学报(英文版)》2010,29(2):5-13

In the present paper, by introducing the effective wave elevation, we transform the extended ellip- tic mild-slope equation with bottom friction, wave breaking and steep or rapidly varying bottom topography to the simplest time-dependent hyperbolic equation. Based on this equation and the empirical nonlinear amplitude dispersion relation proposed by Li et al. (2003), the numerical scheme is established. Error analysis by Taylor expansion method shows that the numerical stability of the present model succeeds the merits in Song et al. (2007)’s model because of the introduced dissipation terms. For the purpose of verifying its performance on wave nonlinearity, rapidly vary- ing topography and wave breaking, the present model is applied to study: (1) wave refraction and diffraction over a submerged elliptic shoal on a slope (Berkhoff et al., 1982); (2) Bragg reflection of monochromatic waves from the sinusoidal ripples (Davies and Heathershaw, 1985); (3) wave transformation near a shore attached breakwater (Watanabe and Maruyama, 1986). Comparisons of the numerical solutions with the experimental or theoretical ones or with those of other models (REF/DIF model and FUNWAVE model) show good results, which indicate that the present model is capable of giving favorably predictions of wave refraction, diffraction, reflection, shoaling, bottom friction, breaking energy dissipation and weak nonlinearity in the near shore zone.  相似文献   

Process-based model for nearshore hydrodynamics, sediment transport and morphological evolution in the surf and swash zones     

R. Bakhtyar  A. Ghaheri  A. Yeganeh-Bakhtiary  D.A. Barry 《Applied Ocean Research》2009,31(1):44-56

Hydrodynamics and sediment transport in the nearshore zone were modeled numerically taking into account turbulent unsteady flow. The flow field was computed using the Reynolds Averaged Navier–Stokes equations with a k–ε turbulence closure model, while the free surface was tracked using the Volume-Of-Fluid technique. This hydrodynamical model was supplemented with a cross-shore sediment transport formula to calculate profile changes and sediment transport in the surf and swash zones. Based on the numerical solutions, flow characteristics and the effects of breaking waves on sediment transport were studied. The main characteristic of breaking waves, i.e. the instantaneous sediment transport rate, was investigated numerically, as was the spatial distribution of time-averaged sediment transport rates for different grain sizes. The analysis included an evaluation of different values of the wave friction factor and an empirical constant characterizing the uprush and backwash. It was found that the uprush induces a larger instantaneous transport rate than the backwash, indicating that the uprush is more important for sediment transport than the backwash. The results of the present model are in reasonable agreement with other numerical and physical models of nearshore hydrodynamics. The model was found to predict well cross-shore sediment transport and thus it provides a tool for predicting beach morphology change.  相似文献   

江苏西洋海域潮流流速剖面参数的相位分析   总被引：1，自引：0，他引：1  

倪志辉  宋志尧 《海洋通报》2009,28(3)

正确地了解潮流流速、水深、粗糙长度,摩阻流速等随时间变化过程的相位关系,对研究浅海潮流的特性有重要的作用.在总结了潮流摩阻流速确定方法的基础上,对江苏西洋海域的实测资料进行了流速剖面参数计算和相位分析,得出结论:①浅海潮流的摩阻流速达到最大值时间要早于平均流速,并从理论上得到验证;②受海底潮流紊动切应力的影响,从表层到底层的流速沿水深随时间变化,底层的最大流速到达时间比上层及表层的要稍微提前;③在一个潮周期中,达到最大值的时间是先摩阻流速和粗糙长度,然后是流速,最后是水深.  相似文献   

某公路滑坡工程治理浅析     

刘正强 《福建地质》2007,26(3):206-209

随着山区公路的大量兴建,将不可避免遇到滑坡灾害,如何成功的治理公路滑坡灾害,将直接决定工程的造价与后期营运的成本。通过介绍某公路滑坡的设计与施工,总结出了滑坡治理应根据各种不同情况,进行认真分析、对比,提出最佳治理方案,方可保证公路建设与营运的安全。  相似文献   

热机碎岩中钻头与胎体温度场的分布研究     

吴景华  张祖培 《地质与勘探》2007,43(4):91-94

主要论述了热机碎岩中钻头与胎体温度场的分布情况,建立了求解胎体和岩石不同位置温度的数学模型;此数学模型的求解与实验数据进行了对比,两者非常接近.  相似文献