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arXiv 0903.1897physics.flu-dynmath-phmath.MP
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Kolmogorov强迫的变分:由简谐强迫驱动的渐近耗散率

Variation on the Kolmogorov Forcing: Asymptotic Dissipation Rate Driven by Harmonic Forcing

B. Rollin, Y. Dubief, C. R. Doering

摘要:

给出了驱动湍流的力的形状与无量纲耗散因子上界$β$之间的关系。我们感兴趣的非平凡(两个以上的波数)强迫功能在一个三维域周期的所有方向。最后,对优化问题的结果与直接数值模拟的结果进行了比较分析。我们报告说,在无限雷诺数的情况下,耗散因子上的边界具有相同的定性行为,在有限雷诺数的耗散因子。正如分析所预测的那样,耗散因子强烈地依赖于力的形状。然而,优化问题不能准确地预测定量行为。我们完成了我们的研究,通过分析平均流量剖面的斯托克斯流量剖面和最佳乘数剖面形状不同的力的形状。我们观察到,在我们的三维周期域中,平均速度剖面和斯托克斯流剖面再现了力形状的所有特征。最佳乘子被证明是与强迫函数的波数的强度。

英文摘要:

The relation between the shape of the force driving a turbulent flow and the upper bound on the dimensionless dissipation factor $β$ is presented. We are interested in non-trivial (more than two wave numbers) forcing functions in a three dimensional domain periodic in all directions. A comparative analysis between results given by the optimization problem and the results of Direct Numerical Simulations is performed. We report that the bound on the dissipation factor in the case of infinite Reynolds numbers have the same qualitative behavior as for the dissipation factor at finite Reynolds number. As predicted by the analysis, the dissipation factor depends strongly on the force shape. However, the optimization problem does not predict accurately the quantitative behavior. We complete our study by analyzing the mean flow profile in relation to the Stokes flow profile and the optimal multiplier profile shape for different force-shapes. We observe that in our 3D-periodic domain, the mean velocity profile and the Stokes flow profile reproduce all the characteristic features of the force-shape. The optimal multiplier proves to be linked to the intensity of the wave numbers of the forcing function.

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