本文關(guān)鍵詞： 二維淺水 有限體積法 Roe格式 植物作用 泥沙輸運 污染物輸移　出處：《大連海洋大學(xué)》2016年碩士論文　論文類型：學(xué)位論文

【摘要】：淺水間斷流動如水躍、涌潮、潰壩波、波浪變形等的數(shù)值研究,因其具有廣泛的工程應(yīng)用背景,引起了許多學(xué)者的研究興趣。然而,自然界的水流運動過程往往不是孤立的,常伴隨有泥沙輸移、污染物遷移轉(zhuǎn)化等物理、化學(xué)和生物過程。其中,潰壩洪水及其誘發(fā)的河床泥沙運動,給下游人民造成重大的生命財產(chǎn)損失。因此,研究動床條件下平面二維潰壩水沙輸移的數(shù)值模擬,在預(yù)測堤壩潰決引起的下游受災(zāi)情況和評估潰壩風(fēng)險控制等方面具有重要的實際意義。另一方面,隨著環(huán)境污染日趨加重,水環(huán)境問題得到越來越多的關(guān)注。要實現(xiàn)對污染水體的治理,了解水體的水動力特征,進(jìn)一步掌握污染物的輸運機(jī)理十分必要。本文首先基于有限體積法和非結(jié)構(gòu)三角形網(wǎng)格建立平面二維淺水?dāng)?shù)學(xué)模型,將模型主要運用于帶有強(qiáng)間斷的潰壩洪水模擬以及具有復(fù)雜地形的海灣潮汐模擬。模型應(yīng)用二階精度的Roe格式近似Riemann解計算網(wǎng)格界面的動量通量,將靜水壓力項作為源項反映在動量方程中,采用高效的干濕處理技術(shù)解決干濕界面的動邊界問題。應(yīng)用模型對6個典型潰壩和3個海灣潮流算例進(jìn)行模擬,實驗結(jié)果良好,展示了本模型強(qiáng)大的適應(yīng)能力和較高的計算精度,說明模型能夠用于工程實踐中�；谝陨纤畡恿δＰ�,考慮平面二維淺水控制方程、泥沙輸移方程以及河床變形方程本文建立了平面二維水沙耦合數(shù)學(xué)模型。其中,淺水控制方程中的連續(xù)方程和水動力方程均采用渾水方程,泥沙連續(xù)方程中泥沙對流通量采用迎風(fēng)格式計算。模型同時考慮了植被對水流、泥沙輸移及床面沖淤變化的影響。應(yīng)用模型對5個算例進(jìn)行模擬,并結(jié)合實測資料對數(shù)值模擬結(jié)果進(jìn)行了驗證分析。計算結(jié)果表明:在模擬動床條件下潰壩水流的演進(jìn)及床面變形等問題上,本文建立的平面二維水沙耦合數(shù)學(xué)模型具有較高的精確度,同時有較好的復(fù)雜地形處理能力。從動床條件下有植物作用的潰壩水流數(shù)值模擬這一算例中可以發(fā)現(xiàn),由于灘地植物的存在,植被區(qū)的水流流速和潰壩波對下游河床的沖刷影響將減少,但同時植被區(qū)河道的泄洪能力也會有所降低,導(dǎo)致洪水在上游區(qū)水位提升�；谒畡恿δＰ�,耦合二維淺水控制方程和物質(zhì)輸運方程,建立平面二維水動力、水質(zhì)顯格式數(shù)學(xué)模型。模型運用高階精度的迎風(fēng)重構(gòu)插值技術(shù)處理網(wǎng)格界面的污染物輸運通量,擴(kuò)散項采用二階精度的離散方法處理。首先模擬理想條件下旋轉(zhuǎn)流場中純對流問題以及純擴(kuò)散問題,以驗證本模型水質(zhì)模塊的計算精度。然后應(yīng)用本模型模擬法國Gironde海灣鹽度分布,以驗證在真實地形條件下模型的計算能力。最后應(yīng)用本模型對莊河海域附近排放的污染物的輸運過程進(jìn)行分析和預(yù)測。數(shù)值結(jié)果表明,在研究水力特性以及預(yù)測沿海水域污染物輸運過程方面,本文所使用的模型是成功的。
[Abstract]:The numerical study of discontinuous flow in shallow water, such as water jump, tidal bore, dam-break wave, wave deformation and so on, has attracted the interest of many scholars because of its extensive engineering application background. However, the natural water flow movement process is often not isolated. Physical, chemical and biological processes, such as sediment transport, pollutant transfer and transformation, are often accompanied. Among them, dam-break floods and their induced sediment movement on the riverbed cause great loss of life and property to the downstream people. It is of great practical significance to study the plane two-dimensional dam-break water and sediment transport under moving bed condition in predicting the downstream disaster caused by the dam break and in assessing the dam-break risk control. On the other hand, as the environmental pollution becomes more and more serious, More and more attention has been paid to the problem of water environment. It is necessary to realize the treatment of polluted water bodies and understand the hydrodynamic characteristics of water bodies. It is necessary to further understand the transport mechanism of pollutants. Firstly, based on the finite volume method and unstructured triangular mesh, a planar two-dimensional shallow water mathematical model is established. The model is mainly applied to the simulation of dam-break flood with strong discontinuity and the tidal simulation of the bay with complex topography. The model uses the second-order precision Roe scheme to approximate the Riemann solution to calculate the momentum flux at the grid interface. The hydrostatic pressure term is reflected as the source term in the momentum equation, and the dynamic boundary problem of the dry and wet interface is solved by using efficient dry and wet treatment technology. Six typical dam-break and three bay tidal current examples are simulated by using the model, and the experimental results are satisfactory. The strong adaptability and high calculation accuracy of the model are demonstrated. It is shown that the model can be used in engineering practice. Based on the hydrodynamic model above, the two-dimensional shallow water governing equation is considered. In this paper, a two-dimensional coupled mathematical model of water and sediment is established, in which the continuous equation and hydrodynamic equation in the governing equation of shallow water adopt muddy water equation. The upwind scheme is used to calculate the sediment flux in the sediment continuum equation. The effects of vegetation on the flow, sediment transport and bed scour and deposition are taken into account in the model. The model is used to simulate five examples. Based on the measured data, the numerical simulation results are verified and analyzed. The results show that the flow evolution and bed surface deformation of dam-break flow under simulated moving bed conditions are discussed. The planar two-dimensional water-sediment coupling mathematical model established in this paper has high accuracy and good ability of complex terrain treatment. It can be found in the numerical simulation of dam-break flow with plant action under the condition of moving bed. Because of the existence of vegetation, the influence of flow velocity and dam-break wave on the downstream riverbed will be reduced, but at the same time, the flood discharge capacity of the channel in the vegetation area will also be reduced, which will lead to the elevation of the flood level in the upstream region, based on the hydrodynamic model. Coupled with two-dimensional shallow water control equation and mass transport equation, a two-dimensional hydrodynamic and water-quality explicit mathematical model is established. The model uses upwind reconstruction interpolation with high order precision to deal with the pollutant transport flux at the grid interface. The diffusion term is treated by a discrete method with second-order accuracy. First, the pure convection problem and the pure diffusion problem in the rotating flow field under ideal conditions are simulated. The model was used to simulate the salinity distribution of Gironde Bay in France. Finally, this model is used to analyze and predict the transport process of pollutants discharged near the Zhuanghe River. The numerical results show that, The model used in this paper is successful in studying hydraulic characteristics and predicting the transport process of pollutants in coastal waters.
【學(xué)位授予單位】：大連海洋大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2016
【分類號】：X52;TV14

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