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

• Published in: Chinese physics B Vol. 20; no. 12; pp. 279 - 292
• Main Author: 蔡伟华 李凤臣 张红娜
• Format: Journal Article
• Language: English
• Published: IOP Publishing 01.12.2011
• Subjects: Decay; Fluid flow; Inhibition; Mathematical analysis; Tensors; Tubes; Turbulence; Turbulent flow; Vorticity; 均匀各向同性湍流; 张量; 直接数值模拟; 联合概率密度; 聚合效应; 聚合物溶液; 衰减; 速度梯度
• ISSN: 1674-1056; 2058-3834; 1741-4199
• DOI: 10.1088/1674-1056/20/12/124702

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.