【正文】 the construction of difference schemes, the proposed features for solving Euler equations and the threetier format symbols secession law [4] and so on. In the pressible N S equations, the calculation method has been great progress, he proposed switching function method, mediation factor method, pact upwind scheme to promote iterative method, nonvolatile no free parameters and dissipative format, munity values are limited to format and pare methods of dissipation [3]. These studies to further improve the accuracy of the calculation method to improve the efficiency of the solution, and the flow field numerical simulation of shock wave have a higher resolving power. And the results of these studies allows us to difference method in CFD research work initially formed its own characteristics. Beginning of the 20th century, 80 years later, puter hardware technology has been rapid development of 10 million submachines, 100 million submachine gradually ing into practical activities. With the calculation method of continuous improvement and development of the theory numerical analysis of highprecision numerical simulation is no longer a fantasy. Meanwhile, along with production practices of human activities in the continuous development of science and technology with each passing day, a large number of hightech industry of putational fluid dynamics made new demands, but also for the development of putational fluid dynamics has provided new opportunities. The constant interaction of theory and practice to form a new hot spot for putational fluid dynamics, new impetus, thus promoting the continuous development of putational fluid dynamics. First of all, in the calculation of models, but also introduced some new models, such as the new largeeddy simulation model, given the effect of wall curvature of the new turbulence model, the new multiphase flow model, the new aircraft aerodynamic analysis and thermal structure of the integration model, etc. [5]. This makes the calculation of putational fluid dynamics model consists of the initial Euler and N S equations, extended to include turbulence, twophase flow, chemical nonequilibrium model of the solar wind and other studies, including a number of models [6]. In which to consider the more mobile mechanisms, such as anisotropy of the nonlinear (stress / strain relationship) turbulence research focus. The results once again proved that universal turbulence model does not yet exist, it is important is how the model accuracy and putation to obtain the better promise。四年時光轉瞬即逝，然而這段短暫時光的點點滴滴都將是我生命中的美好回憶。在生活上，李老師更是平易近人，親人般無微不至的關懷，常帶給我許多溫暖和感動。隨著海洋石油開發(fā)逐步向深海邁進，流體力學的諸多問題更加地為人們所關注。從雙圓柱的模型中可以看出上下兩圓柱相互間有很大的影響，尾渦脫落，擴散出去后相互干擾，出現(xiàn)混雜現(xiàn)象。(2)網(wǎng)格線盡量正交，曲線盡量光滑，不要過分扭曲。（1）圖449渦量圖；圖449渦量明顯比原型減少。這樣，整個結構便表現(xiàn)出疏密不同的網(wǎng)格劃分形式。3 Re 3 ,稱為過渡區(qū)。隨著雷諾數(shù)的增加 ,粘性不可壓縮流體繞圓柱的流動會呈現(xiàn)各種不同的流動狀態(tài) ,在小雷諾數(shù)時，粘性力占主導地位 ,流動是定常的 ,隨著雷諾數(shù)的增加 ,圓柱后會出現(xiàn)一對尾渦。圖49(10) 圖410局部漩渦圖；流體繞過非流線形物體時，物體尾流左右兩側產(chǎn)生的成對的、交替排列的、旋轉方向相反的反對稱渦旋。圖45（6）圖46X方向的渦量等值線局部圖；圖46（7）圖47Y方向的渦量等值線全局圖；圖47（8）圖48Y方向的渦量等值線局部圖；圖48（9）圖49流線圖；流線圖是表征某一時刻流體運動趨勢的圖。4結果分析比較 非定常流情況下的各雷諾數(shù)圓柱繞流 物理模型1的二維圓柱繞流下圖41是用Fluent軟件迭代出來的（1）渦量圖；圖41（2）圖42局部渦量圖；圖42由上面的截圖中可以看出，顏色深的區(qū)域速度大，顏色淺的速度??；從流體學上說，速度大的區(qū)域壓力小，速度小的區(qū)域壓力大；從而得出圓柱繞流模型中上下兩側的流速最大而壓力最小，前后的流速最小而壓力最大。根據(jù)這個原則，我們把有動量方程的離散形式所規(guī)定的壓力與速度的關系代入連續(xù)方程的離散形式，從而得到壓力修正方程，再由壓力修正方程得出的壓力修正值?！坝L”這個概念是相對于局部法向速度定義的。實際上而言，網(wǎng)格的疏密程度與計算迭代的收斂速度以及最終的計算精度緊密相關。 網(wǎng)格的劃分用CFD方法進行流場計算之前，首先要將計算區(qū)域離散化，即劃分網(wǎng)格。早在1878年，捷克科學家Strouhal發(fā)現(xiàn)由一根弦線發(fā)生的風鳴音調，和風速與弦線粗細之商成正比(音調高低決定于弦的振動頻率，而振動頻率實際上反映了瀉渦頻率)。它反映了慣性力與粘性力的比值：其中ρ為流體的密度，U、L分別描述流體的特征速度和結構物的特征長度；μ、υ分別為流體的動力學及運動學粘性系數(shù)。我們可以利用FLUENT求解理想流體與粘性流體，牛頓流體與非牛頓流體，流體熱傳導及擴散問題，可壓流體與不可壓流體，定常與非定常問題，層流與湍流問題等等。1980年，《Numerical Heat Transfer and FluidFlow》中對有限體積法作了全面的闡述。這種方法發(fā)展較早，比較成熟，較多地用于求解雙曲型和拋物型問題。近十多年以來，CFD有了很大的發(fā)展，替代了經(jīng)典流體力學中的一些經(jīng)典計算法和圖解法；過去的一些典型教學實驗，如Reynolds實驗，現(xiàn)在完全可以借助CFD手段在計算機上實現(xiàn)。首先，流動問題的控制方程一般是非線性的，自變量多，計算域的幾何形狀和邊界條件復雜，很難求得解析解，而用CFD方法則有可能找出滿足工程需要的數(shù)值解；其次，可利用計算機進行各種數(shù)值試驗，例如，選擇不同流動參數(shù)進行物理方程中各項有效性和敏感性試驗，從而進行方案比較。由于求解的問題比較復雜，例如NavierStokes方程就是一個十分復雜的非線性方程，數(shù)值求解方法在理論上不是絕對完善的，所以需要通過實驗加以驗證。具體地說就是要建立反映問題各個量之間關系的微分方程及相應的定解條件，這是數(shù)值模擬的出發(fā)點。但是，它往往要求對計算對象進行抽象和簡化，才有可能得出理論解。(Computational Fluid Dynamics)介紹流體力學是一門古老的學科。隨著雷諾數(shù)的增加，粘性不可壓縮流體繞圓柱的流動會呈現(xiàn)各種不同的流動狀態(tài)，在小雷諾數(shù)時，流動是定常的，隨著雷諾數(shù)的增加，圓柱后會出現(xiàn)一對尾渦。本論文應用流體力學的一些基本方程，使用fluent軟件，通過改變網(wǎng)格、空間等計算參數(shù) ,求解了在層流狀態(tài)下，二維非定常的固定圓柱繞流問題，包括單圓柱、雙圓柱的繞流問題，正確地描述了物理現(xiàn)象，得到流場的流函數(shù)等值線圖和速度矢量圖，通過數(shù)值模擬的結果分析漩渦的運動和脫落，升、阻力系數(shù)值的變化,將所得結果數(shù)據(jù)以及結論進行了對比分析。［關鍵詞］ CFD方法；圓柱繞流；數(shù)值模擬；漩渦The Numerical Simulation of Tw0 Dimensional Circular FlowQiuqiSchool of Naval Architecture and Civil Engineering, Zhejiang Ocean University, Zhoushan, Zhejiang 660901［Abstract］This paper applied the CFD method studies in the field of ocean engineering problems of fluid dynamics of water. Numerical methods is its ability to model from the physical model and experimental limitations, has good flexibility, adaptability, wide application, to meet the engineering thesis applied some of the basic equation of fluid mechanics, using the fluent software, by changing the grid space, the parameters are solved in the laminar flow, the fixed twodimensional unsteady flow around a cylinder, including single cylinder, twocylinder flow problem, correctly describes the physical phenomena, Obtained flow field and stream function contours of velocity vector ，the results of the numerical simulation of the movement and shedding vortex, lift and drag coefficient changes, the data and conclusions from the results were pared. And pared with the correct solution, gives reliable results, verify the validity of the numerical solution of the problem. And finally joined in the cylinder is a length behind the right diaphragm was found to inhibit the wake of the formation of vortex shedding.［Key words］ CFD method；Flow around a cylinder；Numerical simulation； Whirlpools1緒論自從1687年牛頓定律公布以來，直到本世紀50年代初，研究流體運動規(guī)律的主要方法有兩種：一是實驗研究，以實驗為研究手