本文關(guān)鍵詞： 大渦模擬 重力流 湍動能譜 擬序結(jié)構(gòu)　出處：《安徽工業(yè)大學(xué)》2014年碩士論文　論文類型：學(xué)位論文

【摘要】：大渦模擬是一種重要的湍流模擬方法，其結(jié)果中包含了湍流中的長度尺度大于濾波寬度的脈動運(yùn)動，它能夠得到比雷諾平均方程方法更多的湍流信息，又比直接數(shù)據(jù)模擬方法所需要的計(jì)算資源少得多。本文采用大渦模擬對前人所做的閘門釋放重力流實(shí)驗(yàn)進(jìn)行了模擬，對比了二維與三維大渦模擬以及雷諾平均模擬的差別，并采用渦耗散模型對二維重力流大渦模擬進(jìn)行了模型改良，分析了重力流的湍動能譜和湍流擬序結(jié)構(gòu)，，討論了非均勻網(wǎng)格和亞格子模型對重力流大渦模擬產(chǎn)生的影響，得出一些結(jié)論如下：（1）三維大渦模擬比二維大渦模擬能夠更好地反映出重力流中的大尺度運(yùn)動，其湍動能譜中存在滿足－5/3冪次律的慣性子區(qū)；（2）大渦模擬能夠再現(xiàn)重力流中兩種不同湍流機(jī)制，非粘性自由剪切及粘性壁面湍流機(jī)制主導(dǎo)的區(qū)域內(nèi)的湍流擬序結(jié)構(gòu)，包括Kelvin-Helmholtz滾動、條帶狀結(jié)構(gòu)和橫向渦擬序結(jié)構(gòu)；（3）三維大渦模擬與三維雷諾平均方法的湍能譜在雷諾平均尺度范圍內(nèi)重合，在脈動尺度范圍內(nèi)兩者出現(xiàn)了分離，并且在雷諾平均方法的湍能譜中沒有觀察到實(shí)驗(yàn)和理論都已經(jīng)證明了的－5/3冪次律。（4）膨脹系數(shù)為恒定1.03以下非均勻網(wǎng)格帶來的交換誤差對三維大渦模擬結(jié)果產(chǎn)生的影響比較小，說明我們所采用的三維大渦模擬可以在非均勻網(wǎng)格上進(jìn)行；（5）比較了動力Smagorinsky模型、標(biāo)準(zhǔn)Smagorinsky模型以Liu-Meneveau-Katz尺度相似模型，結(jié)果顯示動力Smagorinsky模型模擬效果最好，Liu-Meneveau-Katz尺度相似模型最差；但是Liu-Meneveau-Katz尺度相似模型與標(biāo)準(zhǔn)Smagorinsky模型的混合模型的模擬效果與動力Smagorinsky模型相近，且所需要的計(jì)算代價(jià)小于動力Smagorinsky模型。上述研究成果對于后續(xù)的在復(fù)雜地形上含有沉積物的重力流研究中應(yīng)用大渦模擬有一定的參考作用。
[Abstract]:Large eddy simulation is an important turbulence simulation method, whose results include the pulsating motion of the length scale larger than the filter width in the turbulence, which can obtain more turbulence information than the Reynolds average equation method. In this paper, a large eddy simulation is used to simulate the gravity flow from the gate. The differences between 2D and 3D large vortices simulation and Reynolds average simulation are compared, and the vortex-dissipation model is used to improve the two-dimensional gravity flow simulation. The turbulent kinetic energy spectrum and turbulent sequence structure of gravity flow are analyzed. The influence of non-uniform grid and sub-lattice model on the large eddy simulation of gravity flow is discussed. Some conclusions are as follows: (1) Three-dimensional large eddy simulation can better reflect the large-scale motion in gravity flow than two-dimensional large eddy simulation, and there is an inertial sub-region in the turbulent kinetic energy spectrum which satisfies the -5 / 3 power law. 2) large eddy simulation can reproduce the turbulent quasi-sequence structure in the region dominated by non-viscous free shear and viscous wall turbulence. It includes Kelvin-Helmholtz rolling, strip structure and transverse vortex structure. 3) the turbulent spectra of 3-D large eddy simulation and 3-D Reynolds mean method coincide in the range of Reynolds mean scale, and they are separated in the range of pulsating scale. And in the turbulent energy spectrum of the Reynolds mean method, the law of -5 / 3 power law, which has been proved by both experiment and theory, has not been observed. The exchange error caused by the inhomogeneous mesh with a constant expansion coefficient below 1.03 has little effect on the results of 3D large eddy simulation. The results show that the 3D large eddy simulation can be carried out on a non-uniform grid. The dynamic Smagorinsky model and the standard Smagorinsky model are compared with the Liu-Meneveau-Katz scale similarity model. The results show that the dynamic Smagorinsky model is the best and the Liu-Meneveau-Katz scale model is the worst. However, the simulation effect of the mixed model of Liu-Meneveau-Katz scale similarity model and standard Smagorinsky model is similar to that of dynamic Smagorinsky model. The computational cost required is less than that of the dynamic Smagorinsky model. The results mentioned above can be used as a reference for the subsequent study of gravity flow with sediment on complex terrain using large eddy simulation. .
【學(xué)位授予單位】：安徽工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TV135

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本文編號：1485679