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Sensitivity analysis of the second and third-order velocity structure functions to the Reynolds number in decaying and forced isotropic turbulence using the EDQNM model
European Journal of Mechanics - B/Fluids ( IF 2.6 ) Pub Date : 2021-04-17 , DOI: 10.1016/j.euromechflu.2021.04.003
M. Meldi , L. Djenidi , R.A. Antonia

Numerical calculations based on a recent version of the eddy-damped quasi-normal model (EDQNM-LMFA) are carried out for homogeneous isotropic turbulence (HIT) with the aim of investigating the dependency on the Reynolds number of second and third order velocity structure functions. The quantities investigated include the energy spectrum E, the non-linear energy transfer T as well as the second (S2) and third (S3) order moments of the longitudinal velocity increment. Both free decaying HIT and (steady state) forced HIT are considered. The analysis of the structure functions for Reλ[50,106] indicates that, regardless of whether one considers decaying or forced HIT, the large scales affect S2 and S3 in the scaling range. In that range, forcing affects S2 and S3 differently. For forced HIT, S2(ϵ¯r)23 exhibits a distinct “bump” near the upper end of the scaling range while no such bump is seen for S3(ϵ¯r). The latter quantity remains approximately constant for values of r which extend to the scale corresponding to the forcing. For decaying HIT, there is no discernible bump in either S2(ϵ¯r)23 or S3(ϵ¯r). The slope of S3 in the scaling range approaches the theoretical value of 1, when Reλ is sufficiently large. However, at similar Reλ, the slope of S2 has not yet reached a constant for either decaying or forced HIT.



中文翻译:

使用EDQNM模型对二阶和三阶速度结构函数对衰减和强迫各向同性湍流中的雷诺数的敏感性分析

为了研究二阶和三阶速度结构函数对雷诺数的依赖性,基于最新版本的涡阻尼准正态模型(EDQNM-LMFA)进行了数值计算,用于均质各向同性湍流(HIT)。 。研究的数量包括能谱E,非线性能量转移 Ť 以及第二个(小号2个)和第三个(小号3)纵向速度增量的阶矩。自由衰减HIT和(稳态)强制HIT都被考虑了。的结构功能分析[RËλ[501个06] 表示,无论是考虑衰减还是强制HIT,大规模影响 小号2个小号3在缩放范围内。在此范围内,强迫会影响小号2个小号3不一样。对于强制命中,小号2个ϵ¯[R2个3 在缩放范围的上限附近显示出明显的“凹凸”,而对于 小号3ϵ¯[R。对于的值,后一个量保持近似恒定[R延伸到与强迫相对应的比例。对于衰减的HIT,两者中都没有明显的颠簸小号2个ϵ¯[R2个3 或者 小号3ϵ¯[R。的斜率小号3 在标度范围内接近1的理论值 [RËλ足够大。但是,类似[RËλ,斜率 小号2个 衰减或强制HIT尚未达到常数。

更新日期:2021-04-24
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