Direct numerical simulation study of the interaction between the polymer effect and velocity gradient tensor in decaying homogeneous isotropic turbulence

作者：Cai Wei-Hua; Li Feng-Chen^*; Zhang Hong-Na

来源：Chinese Physics B, 2011, 20(12): 124702.

DOI：10.1088/1674-1056/20/12/124702

• decaying homogeneous isotropic turbulence
• turbulent drag-reducing flow
• velocity gradient tensor
• direct numerical simulation

Direct numerical simulation of decaying homogeneous isotropic turbulence (DHIT) of a polymer solution is performed. In order to understand the polymer effect on turbulence or additive-turbulence interaction, we directly investigate the influence of polymers on velocity gradient tensor including vorticity and strain. By visualizing vortex tubes and sheets, we observe a remarkable inhibition of vortex structures in an intermediate-scale field and a small-scale field but not for a large scale field in DHIT with polymers. The geometric study indicates a strong relevance among the vorticity vector, rate-of-strain tensor, and polymer conformation tensor. Joint probability density functions show that the polymer effect can increase "strain generation resistance" and "vorticity generation resistance", i.e., inhibit the generation of vortex sheets and tubes, ultimately leading to turbulence inhibition effects.

• 出版日期2011-12
• 单位哈尔滨工业大学