本文選題：均勻各向同性湍流 + Rogallo初始化方法�。� 參考：《力學(xué)學(xué)報》2016年06期

【摘要】：均勻各向同性湍流是一種最簡單的湍流理想狀態(tài),也是湍流基礎(chǔ)理論研究的最重要對象之一.為了用數(shù)值方法產(chǎn)生均勻各向同性湍流場,一般采用Rogallo提出的方法在譜空間生成初始場,然后再轉(zhuǎn)換到物理空間.研究表明,由該方法生成的初始湍流場在3個棱向上呈各向異性,在結(jié)構(gòu)函數(shù)和速度概率密度分布上均有體現(xiàn).盡管在初始場樣本很多時,這種各向異性可以在平均意義上消除,但作為數(shù)值模擬采用的單個流場則波動較大,不利于在實際計算中作為單個初始場生成各向同性湍流.在此基礎(chǔ)上提出一種改進的Rogallo初始化方法,稱為模量平均法,將Rogallo方法在3個軸向分別進行,并進行模量平均,最后采用能譜進行模量控制.這種方法可以一方面保持初始場能譜,另一方面減小單個流場的各向異性波動,以產(chǎn)生各向同性程度更佳的單個初始場.在統(tǒng)計意義上,新方法可以分別將結(jié)構(gòu)函數(shù)和速度概率密度的相對標(biāo)準(zhǔn)差減小約10%.
[Abstract]:Homogeneous isotropic turbulence is one of the simplest ideal turbulent states and one of the most important objects in the basic theory of turbulence. In order to generate homogeneous isotropic turbulent field by numerical method, the method proposed by Rogallo is generally used to generate the initial field in spectral space and then to be converted to physical space. The results show that the initial turbulence field generated by this method is anisotropic up to three edges and can be found in both the structure function and the velocity probability density distribution. Although this anisotropy can be eliminated in the average sense when there are a large number of initial field samples, the single flow field, which is used for numerical simulation, fluctuates greatly, which is not conducive to the generation of isotropic turbulence as a single initial field in the actual calculation. On this basis, an improved Rogallo initialization method, called modulus averaging method, is proposed. The Rogallo method is carried out separately in three axes, and the modulus is averaged. Finally, the modulus is controlled by energy spectrum. This method can preserve the energy spectrum of the initial field on the one hand and reduce the anisotropic fluctuation of the single flow field on the other to produce a single initial field with better isotropy. In the statistical sense, the new method can reduce the relative standard deviation of the structure function and the velocity probability density by about 10 parts respectively.
【作者單位】： 北京航空航天大學(xué)中法工程師學(xué)院;法國里昂中央理工大學(xué)流體與聲學(xué)實驗室;
【基金】：國家自然科學(xué)基金資助項目(11202013,11302012,51420105008)
【分類號】：O357.5

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