冰底形态对流场特性影响的数值模拟研究
发布时间：2018-08-26 16:57
【摘要】：海冰作为影响全球气候变化的一个重要因素,近些年越来越受到物理海洋学家、气候学家的广泛关注。海冰运动作为全球水循环过程的重要环节之一,对寒区海上经济活动以及资源开发有着重要的影响和作用。海冰在海洋、大气的动力强迫作用下的运动变化、动量传输及其断裂、重叠和堆积等动力学特性是海冰动力学主要研究内容。海冰与大气、海洋间的动力作用主要表现为风、流对海冰的拖曳力,这与用于描述海冰动力学模型中的参数—拖曳系数有着直接关系。由于海冰所受的风、流拖曳力的大小直接影响到海冰漂移速度、轨迹,甚至关系到海冰间相互作用的动力和破坏等问题,因此从上个世纪50年代起就开始对海冰拖曳系数进行了广泛研究。 根据现场海冰观测及传统海冰拖曳系数测量法涡动法、剖面法、动量法已得到过某些海域海冰的拖曳系数值,但往往均取为定值且多集中在冰-气界面上,同时具有较大的离散型。为了提高拖曳系数的准确性,完善海冰动力学模型的精度,海冰拖曳系数的参数化方法研究已经成为海冰动力学模型中的研究重点。本文将在开展的冰下流场观测的物理模型实验基础上,采用数值模拟方法对冰下流场的实验数据进行进一步的拓展,从而可得到冰下流场的一些定性规律,并获得孤立冰块形拖曳系数、摩拖曳系数和冰几何参数之间的关系,为将来海冰拖曳系数参数化提供基础的技术支持。同时,数值模拟还可以对物理模型实验中没有观测到的现象进行研究,进一步深入了解冰-水动力相互作用的细节问题。 论文主要内容分为以下五章：第一章绪论部分,主要介绍了课题研究背景及国内外研究概况和发展趋势,阐述本研究理论意义和应用价值。第二章在简要概括传统获取拖曳系数方法的基础上,重点介绍海冰拖曳系数参数化的主要思想及具体过程。描述相关物理拖曳实验方案与过程,其中包括拖曳力的测量装置及实验工况安排等。第三章是建立二维数学模型,介绍相应的数值模拟方法包括控制方程、湍流模型、网格划分及边界条件设定和数值计算方法等。第四章为数值模拟及模型实验结果对比验证。针对光滑冰底冰块进行二维数值模拟,分别得到5种不同入水深度、8种水流速度共40种工况下的冰下流场分布及冰块所受流体拖曳力。分析了冰下及冰后流场动力学特性。结果显示,数值计算结果与物模实验结果吻合较好,从而验证了该数值模型在模拟冰下流场及拖曳力时的有效性。第五章针对两种不同底纹倾角的粗糙底面浮冰模型进行了数值模拟。分析各工况下流场分布特性及相互之间的联系、计算浮冰所受拖曳力值并与实验结果进行对比。结果表明：同种水深下,粗糙冰底浮冰模型的冰下流场受影响区域范围随底纹角度的增加而增大,且30。倾角产生的涡的范围在冰下流场要大于15。情况。而同种水深及速度条件下浮冰所受总拖曳力随底纹角度变化较小。
[Abstract]:As an important factor affecting global climate change, sea ice has attracted more and more attention from physical oceanographers and climatologists in recent years. As an important part of the global water cycle process, sea ice movement plays an important role in marine economic activities and resource development in cold regions. The dynamic characteristics of sea ice, such as motion variation, momentum transmission, breakage, overlap and accumulation, are the main research contents of sea ice dynamics. The magnitude of current drag force has a direct impact on the drift velocity and trajectory of sea ice, and even on the dynamics and destruction of sea ice interaction. Therefore, the drag coefficient of sea ice has been extensively studied since the 1950s.
The drag coefficients of sea ice in some sea areas have been obtained by eddy method, section method and momentum method according to the field sea ice observation and the traditional sea ice drag coefficient measurement method, but they are usually fixed values and mostly concentrated on the ice-air interface. At the same time, they have a large discrete type. The parameterization method of the drag coefficient of sea ice has become the focus of the study in the dynamic model of sea ice. Based on the physical model experiment of the observation of the flow field under ice, the experimental data of the flow field under ice are further expanded by the numerical simulation method, and some qualitative laws of the flow field under ice can be obtained. The relationships among drag coefficients of isolated ice blocks, drag coefficients and geometric parameters of ice are obtained to provide basic technical support for parameterization of drag coefficients of sea ice in the future.
The main content of this paper is divided into five chapters as follows: Chapter 1 is the introduction, which mainly introduces the background of the research, the general situation and the development trend of the research at home and abroad, and expounds the theoretical significance and application value of this study. The third chapter is to establish a two-dimensional mathematical model. The corresponding numerical simulation methods are introduced, including control equations, turbulence models, meshing, boundary conditions setting and numerical calculation methods. Numerical simulation and model test results were compared and verified. Five different water entry depths, eight water velocities and 40 working conditions were obtained respectively. The dynamic characteristics of the flow field under and after ice were analyzed. The experimental results are in good agreement, which verifies the validity of the numerical model in simulating the flow field and drag force under ice. Chapter 5 simulates the rough ice floe model with two different inclination angles. The distribution characteristics of the flow field and the relationship between them are analyzed, and the drag force on the ice floe is calculated and compared with the experimental results. The results show that under the same water depth, the range of the affected area increases with the increase of the bottom grain angle, and the range of the vortex generated by the inclination angle is larger than 15.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：P731.15
本文编号：2205562
[Abstract]:As an important factor affecting global climate change, sea ice has attracted more and more attention from physical oceanographers and climatologists in recent years. As an important part of the global water cycle process, sea ice movement plays an important role in marine economic activities and resource development in cold regions. The dynamic characteristics of sea ice, such as motion variation, momentum transmission, breakage, overlap and accumulation, are the main research contents of sea ice dynamics. The magnitude of current drag force has a direct impact on the drift velocity and trajectory of sea ice, and even on the dynamics and destruction of sea ice interaction. Therefore, the drag coefficient of sea ice has been extensively studied since the 1950s.
The drag coefficients of sea ice in some sea areas have been obtained by eddy method, section method and momentum method according to the field sea ice observation and the traditional sea ice drag coefficient measurement method, but they are usually fixed values and mostly concentrated on the ice-air interface. At the same time, they have a large discrete type. The parameterization method of the drag coefficient of sea ice has become the focus of the study in the dynamic model of sea ice. Based on the physical model experiment of the observation of the flow field under ice, the experimental data of the flow field under ice are further expanded by the numerical simulation method, and some qualitative laws of the flow field under ice can be obtained. The relationships among drag coefficients of isolated ice blocks, drag coefficients and geometric parameters of ice are obtained to provide basic technical support for parameterization of drag coefficients of sea ice in the future.
The main content of this paper is divided into five chapters as follows: Chapter 1 is the introduction, which mainly introduces the background of the research, the general situation and the development trend of the research at home and abroad, and expounds the theoretical significance and application value of this study. The third chapter is to establish a two-dimensional mathematical model. The corresponding numerical simulation methods are introduced, including control equations, turbulence models, meshing, boundary conditions setting and numerical calculation methods. Numerical simulation and model test results were compared and verified. Five different water entry depths, eight water velocities and 40 working conditions were obtained respectively. The dynamic characteristics of the flow field under and after ice were analyzed. The experimental results are in good agreement, which verifies the validity of the numerical model in simulating the flow field and drag force under ice. Chapter 5 simulates the rough ice floe model with two different inclination angles. The distribution characteristics of the flow field and the relationship between them are analyzed, and the drag force on the ice floe is calculated and compared with the experimental results. The results show that under the same water depth, the range of the affected area increases with the increase of the bottom grain angle, and the range of the vortex generated by the inclination angle is larger than 15.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：P731.15
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