不同涡粘性湍流底边界层特征量研究

发布时间：2018-05-04 22:06

本文选题：固体悬浮液 + 变换场方法　；参考：《中国科学院研究生院（海洋研究所）》2014年博士论文

【摘要】：湍流底边界层的物理性质和动力过程十分复杂，其水动力特征对于海洋工程、海洋生物等学科具有重要的研究意义和应用价值。但是由于其特殊的地理位置和复杂的动力系统，观测数据和理论模型非常难获得，一直是物理海洋学、海洋环境工程及生物学研究的热点之一。本论文主要的工作：一方面从理论上研究了海底悬浮液的有效粘性的消减机制；另一方面通过建立两种新的涡粘性参数化形式，建立湍流底边界层动力系统的理论模式并得到其解析解。研究内容可分为三个方面： 1.在高浓度悬浮液的条件下，利用变换场理论，根据Stokes方程，研究了悬浮液的有效粘性随颗粒尺度的变化特征。统计结果表明：一定的颗粒浓度下（中或高），在一个元胞内增加颗粒的尺度或者减少单位体积内的颗粒数量，可大幅度地减小固体悬浮液的有效粘性。本工作揭示了固体颗粒尺度的变化可控制悬浮液的有效粘性的机制。 2.给出新的参数化垂直涡粘性的三次多项式形式az2(1z/d)，基于简化的Navier Stokes方程，利用超几何函数的方法，，得到了湍流粗糙底边界层的动力系统的解析解。另外，推导出湍流底边界层的其他的动力参数，如底剪应力，Ekman传输，Ekman抽吸及近底部速度分布场，从理论上研究了湍流底边界层特征量的分布特征。进一步，通过数值结果的分析，得出底边界层的总速度，亏损速度及其剪应力受平均流的角频率和地球自转影响比较大；而底边界层的动力结构对于底边界层顶部粗糙度不敏感。 3.推导出在另一个新的涡粘性形式az (1z/d)2下的湍流底边界层的动力系统的解析解。并且通过数值分析得到：湍流底边界层的速度剖面同样对于平均流的角频率和地球自转影响之比依赖性较大；但是对于底边界层顶部粗糙度不敏感。通过和潮流的实际观测数据对比，在速度的振幅上拟合基本一致。本论文的工作从理论上研究了湍流边界层涡粘性的影响机制和参数化形式，是研究底边界层的动力影响因素重要的手段和方法。
[Abstract]:The physical properties and dynamic processes of turbulent bottom boundary layer are very complex. The hydrodynamic characteristics of turbulent bottom boundary layer are of great significance and application value for marine engineering and marine biology. However, because of its special geographical location and complex dynamic system, observation data and theoretical models are very difficult to obtain, which has been one of the hot spots in physical oceanography, marine environmental engineering and biology. The main work of this thesis is as follows: on the one hand, the effective viscosity reduction mechanism of submarine suspensions is theoretically studied; on the other hand, two new parameterized forms of vortex viscosity are established. The theoretical model of turbulent bottom boundary layer dynamic system is established and its analytical solution is obtained. The research contents can be divided into three aspects: 1. Under the condition of high concentration of suspensions, the change characteristics of effective viscosity of suspensions with particle size are studied by using the transform field theory and Stokes equation. The statistical results show that the effective viscosity of solid suspensions can be greatly reduced by increasing the size of particles or reducing the number of particles per unit volume in a cell at a certain particle concentration (medium or high). This work reveals the mechanism that the change of solid particle size can control the effective viscosity of suspensions. 2. In this paper, a new parameterized cubic polynomial form of vertical vorticity is given. Based on the simplified Navier Stokes equation, the analytical solution of the turbulent dynamic system of rough bottom boundary layer is obtained by using the method of hypergeometric function. In addition, other dynamic parameters of the turbulent bottom boundary layer, such as the bottom shear stress Ekman transport Ekman pumping and the velocity distribution near the bottom, are derived, and the distribution characteristics of the turbulent bottom boundary layer characteristic quantities are theoretically studied. Further, through the analysis of the numerical results, it is concluded that the total velocity, the depleted velocity and the shear stress of the bottom boundary layer are greatly affected by the angular frequency of the average flow and the rotation of the earth. The dynamic structure of the bottom boundary layer is insensitive to the top roughness of the bottom boundary layer. 3. An analytical solution for the dynamic system of the turbulent bottom boundary layer is derived under another new form of vortex-viscosity, Az / D ~ (2). The numerical results show that the velocity profile of the turbulent bottom boundary layer is also dependent on the ratio of the angular frequency of the mean flow to the rotation of the earth, but it is not sensitive to the top roughness of the bottom boundary layer. By comparing with the observed data of the tidal current, the fitting of the velocity amplitude is basically consistent. In this paper, the influence mechanism and parameterized form of vortex viscosity in turbulent boundary layer are studied theoretically, which is an important means and method to study the dynamic influence factors of bottom boundary layer.
【学位授予单位】：中国科学院研究生院（海洋研究所）
【学位级别】：博士
【学位授予年份】：2014
【分类号】：P731.26

【参考文献】