【摘要】：海冰作為影響全球氣候變化的一個重要因素,近些年越來越受到物理海洋學家、氣候學家的廣泛關注。海冰運動作為全球水循環(huán)過程的重要環(huán)節(jié)之一,對寒區(qū)海上經濟活動以及資源開發(fā)有著重要的影響和作用。海冰在海洋、大氣的動力強迫作用下的運動變化、動量傳輸及其斷裂、重疊和堆積等動力學特性是海冰動力學主要研究內容。海冰與大氣、海洋間的動力作用主要表現(xiàn)為風、流對海冰的拖曳力,這與用于描述海冰動力學模型中的參數(shù)—拖曳系數(shù)有著直接關系。由于海冰所受的風、流拖曳力的大小直接影響到海冰漂移速度、軌跡,甚至關系到海冰間相互作用的動力和破壞等問題,因此從上個世紀50年代起就開始對海冰拖曳系數(shù)進行了廣泛研究。 根據(jù)現(xiàn)場海冰觀測及傳統(tǒng)海冰拖曳系數(shù)測量法渦動法、剖面法、動量法已得到過某些海域海冰的拖曳系數(shù)值,但往往均取為定值且多集中在冰-氣界面上,同時具有較大的離散型。為了提高拖曳系數(shù)的準確性,完善海冰動力學模型的精度,海冰拖曳系數(shù)的參數(shù)化方法研究已經成為海冰動力學模型中的研究重點。本文將在開展的冰下流場觀測的物理模型實驗基礎上,采用數(shù)值模擬方法對冰下流場的實驗數(shù)據(jù)進行進一步的拓展,從而可得到冰下流場的一些定性規(guī)律,并獲得孤立冰塊形拖曳系數(shù)、摩拖曳系數(shù)和冰幾何參數(shù)之間的關系,為將來海冰拖曳系數(shù)參數(shù)化提供基礎的技術支持。同時,數(shù)值模擬還可以對物理模型實驗中沒有觀測到的現(xiàn)象進行研究,進一步深入了解冰-水動力相互作用的細節(jié)問題。 論文主要內容分為以下五章：第一章緒論部分,主要介紹了課題研究背景及國內外研究概況和發(fā)展趨勢,闡述本研究理論意義和應用價值。第二章在簡要概括傳統(tǒng)獲取拖曳系數(shù)方法的基礎上,重點介紹海冰拖曳系數(shù)參數(shù)化的主要思想及具體過程。描述相關物理拖曳實驗方案與過程,其中包括拖曳力的測量裝置及實驗工況安排等。第三章是建立二維數(shù)學模型,介紹相應的數(shù)值模擬方法包括控制方程、湍流模型、網格劃分及邊界條件設定和數(shù)值計算方法等。第四章為數(shù)值模擬及模型實驗結果對比驗證。針對光滑冰底冰塊進行二維數(shù)值模擬,分別得到5種不同入水深度、8種水流速度共40種工況下的冰下流場分布及冰塊所受流體拖曳力。分析了冰下及冰后流場動力學特性。結果顯示,數(shù)值計算結果與物模實驗結果吻合較好,從而驗證了該數(shù)值模型在模擬冰下流場及拖曳力時的有效性。第五章針對兩種不同底紋傾角的粗糙底面浮冰模型進行了數(shù)值模擬。分析各工況下流場分布特性及相互之間的聯(lián)系、計算浮冰所受拖曳力值并與實驗結果進行對比。結果表明：同種水深下,粗糙冰底浮冰模型的冰下流場受影響區(qū)域范圍隨底紋角度的增加而增大,且30。傾角產生的渦的范圍在冰下流場要大于15。情況。而同種水深及速度條件下浮冰所受總拖曳力隨底紋角度變化較小。
[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.
【學位授予單位】：大連理工大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：P731.15

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