论文标题
在湍流中前进的颗粒的标量吸收
Scalar absorption by particles advected in a turbulent flow
论文作者
论文摘要
我们研究了湍流波动对示踪剂颗粒吸收标量场的拉格朗日统计的影响，这是悬浮的非运动微生物的营养吸收模型。通过对欧拉 - 拉格朗日模型的广泛直接数值模拟，我们根据舍伍德数量量化了由湍流引起的标量吸收的增加及其对Peclet和Reynolds数字的依赖。将数值结果与此处扩展的固定剪切流的经典预测进行了比较，以考虑到恢复标量通量的存在。我们发现，平均场预测与低卵石数量低的数值模拟一致，但无法描述针对大型PECLET数字观察到的局部标量摄取的大波动。我们还通过查看局部剪切速率和摄取速率之间的时间相关性来研究速度波动在局部吸收中的作用，我们发现后者遵循kolmogorov时间尺度给出的流体速度波动，并延迟。还讨论了我们的结果与水生微生物的相关性。
We investigate the effects of turbulent fluctuations on the Lagrangian statistics of absorption of a scalar field by tracer particles, as a model for nutrient uptake by suspended non-motile microorganisms. By means of extensive direct numerical simulations of an Eulerian-Lagrangian model we quantify, in terms of the Sherwood number, the increase of the scalar uptake induced by turbulence and its dependence on the Peclet and Reynolds numbers. Numerical results are compared with classical predictions for a stationary shear flow extended here to take into account the presence of a restoring scalar flux. We find that mean field predictions agree with numerical simulations at low Peclet numbers but are unable to describe the large fluctuations of local scalar uptake observed for large Peclet numbers. We also study the role of velocity fluctuations in the local uptake by looking at the temporal correlation between local shear and uptake rate and we find that the latter follows fluid velocity fluctuations with a delay given by Kolmogorov time scale. The relevance of our results for aquatic microorganisms is also discussed.
