On the alignment dynamics of a passive scalar gradient in a two-dimensional flow
On the alignment dynamics of a passive scalar gradient in a two-dimensional flow
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二维流中被动标量梯度的排列动力学
DOI：
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发表时间：
2005
期刊：
影响因子：
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通讯作者：
P. Paranthoën
中科院分区：
文献类型：
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作者：
A. Garcia;M. Gonzalez;P. Paranthoën
被动标量梯度的方向的统计特性的拉格朗日研究进行实验数据和一个简单的，数值分析。结果表明，在低雷诺数Benard-von Karman街道，加热线源下游的温度梯度不符合Lapeyre等人的模型[Phys. Fluids 11，3729（1999）]在双曲线区域预测的渐近方向。这一结果归因于应变持续性沿沿着拉格朗日轨迹的波动。的标量梯度对齐属性的数值分析表明，这些波动，连同低水平的应变率，可能会导致优先取向是从理论上的一个不同的渐近模型预测。
A Lagrangian study of the statistical properties of the orientation of a passive scalar gradient is performed using experimental data and a simple, numerical analysis. It is shown that, in a low-Reynolds number Benard-von Karman street, the temperature gradient downstream of a heated line source does not align with the asymptotic orientation predicted by the Lapeyre et al. model [Phys. Fluids 11, 3729 (1999)] in the hyperbolic regions. This result is ascribed to fluctuations of strain persistence along Lagrangian trajectories. A numerical analysis of the scalar gradient alignment properties shows that these fluctuations, together with a low level of the rate of strain, may lead to preferential orientations that are different from the theoretical one predicted by an asymptotic model.