Hybrid simulations for the mechanical degradation of polymer solution by turbulence

在这项研究中，我们研究了机械降解的聚合物溶液的湍流和湍流统计的影响进行数值模拟，其中包括切断过程的长链聚合物。众所周知，聚合物添加剂可降低湍流的动能耗散。结果发现，长链聚合物有较大的影响，湍流统计的动能耗散一样。当聚合物的弹性强得多时，即使湍流充分衰减，通过拉伸聚合物也能维持湍流运动。动能谱在Kolmogorov尺度以下的波数范围内表现出特征性的幂律衰减。我们还发现，随着时间的推移，由于切割减少了长链聚合物的数量，动能耗散的减少率逐渐降低。

In this study we examined the mechanical degradation of polymer solution by turbulence and its effects on turbulence statistics by performing the numerical simulations which include the cut-off process of long-chain polymers. It is known that the kinetic energy dissipation of turbulent flows is reduced by polymer additives. It was found that the longer chain polymers have larger influence on the turbulence statistics like the kinetic energy dissipation. When the elasticity of polymers was much stronger, turbulent motions were maintained by stretching polymers even when the turbulence sufficiently decayed. Then the kinetic energy spectrum showed the characteristic power-law decay in the wavenumber range below the Kolmogorov scale. We also found that the reduction rate of the kinetic energy dissipation was gradually decreased with time due to the decreasing of the number of longer chain polymers by cutting.