脉动风场中跃移运动的数值模拟 Alternative Title Numerical Simulation of Wind-Blown Sand Saltation in Random Wind Field 崔军强 Thesis Advisor 武生智 2013-05-24 Degree Grantor 兰州大学 Place of Conferral 兰州 Degree Name 硕士 Keyword 风沙运动 脉动 质量通量 跃移 随机模型 Abstract 沙粒在风的作用下的运动主要是跃移。在风沙运动研究中，我们一般只考虑平均风速，并不考虑脉动风速对颗粒运动的影响，但是，忽略脉动部分对运动颗粒的影响，将直接影响颗粒运动的结果。本学位论文通过数值仿真大气边界层中风速脉动对跃移运动的影响，为实验研究和理论分析提供一定的参照。主要研究内容如下： 1．首先对风沙流中随机风场的数学模型进行了具体描述，进而利用kinematic simulation给出具体的随机Fourier脉动风场方程。 2．利用生成的随机脉动风场，分别模拟了单一粒径和混合粒径床面的颗粒跃移运动。在单一粒径下，得到了风速与摩阻速度和傅里叶节点数之间的关系，进而确定了节点数的取值。同时模拟得到了跃移运动时的垂直质量通量,水平质量通量和单宽输沙率随摩阻速度的变化规律，并与实验值做了比较。 3．在混合粒径时，模拟得到了跃移运动时，颗粒的垂直质量通量和水平质量通量和单宽输沙率随摩阻速度的变化规律，并与实验值相比较。同时，我们研究了运动达到稳态时的颗粒分布与摩阻速度的关系。 4．考虑脉动风场时，我们得到的数值模拟结果与实验结果相比，模拟结果和实验值两者吻合的很好，这说明了脉动在实际的颗粒运动中有一定的作用，不可以忽略。 Other Abstract The main model of aeolian sand is saltation. Saltation can eject dust aerosols into the atmosphere, create sand dunes, and erode geological features. In the study of sand movement, generally, we only consider the mean wind speed, ignoring the impact of fluctuating wind speed on particle motion. However, ignoring the fluctuating part of the moving particles will directly affect the results of the quantitative study of particle motion. Therefore, the research of fluctuating wind speed’s effect on saltation is very important. This thesis is about the numerical simulation of saltation under wind speed fluctuating in the atmospheric boundary layer to provide some references for experimental research and theoretical analysis. In the study, saltation of the single size bed and mixed size bed is studied. The main contents are as follows: 1. A specific description of the mathematical model of stochastic wind field is put forward at first. Then the kinematic simulation gives specific random Fourier fluctuating wind field equations and generates specific random fluctuations. We use the random Fourier series to generate the independent vector component (such as frequency, wave number, etc.) in the fluctuating wind field. The parameters to the control of random fluctuations in this study, such as frequency, takes the mean of 0 and standard deviation of a Gaussian random distribution, and wave number takes the mean for 0 and a standard deviation of 0.5 Gaussian random distribution. 2. Under the random fluctuating wind field, we simulate particle motion of single size and mixed size bed. For the single size bed, we get the relationship between wind speed and the friction velocity and Fourier nodes, and determine the value of the number of nodes. After the number of nodes is determined, we conduct a comparison of the numerical fluctuating wind speed and the experimental fluctuating wind speed. The results show well consistency. We simulate the sediment transport rate with the variation of the friction velocity. And the results are compared with the experimental values and the classical formula. The results of our simulation are better. Vertical mass flux and horizontal mass flux of particles and the change of sand particle size distribution are obtained too. 3. For mixed particle size bed, we obtain the number of nodes firstly. Then we compare the experimental fluctuating wind speed and the simulation fluctuating wind speed. The results is identical with that of the ... URL 查看原文 Language 中文 Document Type 学位论文 Identifier https://ir.lzu.edu.cn/handle/262010/226104 Collection 土木工程与力学学院 Recommended CitationGB/T 7714 崔军强. 脉动风场中跃移运动的数值模拟[D]. 兰州. 兰州大学,2013.
 Files in This Item: There are no files associated with this item.
 Related Services Recommend this item Bookmark Usage statistics Export to Endnote Altmetrics Score Google Scholar Similar articles in Google Scholar [崔军强]'s Articles Baidu academic Similar articles in Baidu academic [崔军强]'s Articles Bing Scholar Similar articles in Bing Scholar [崔军强]'s Articles Terms of Use No data! Social Bookmark/Share
No comment.