Abstract We experimentally study the propagation of vortex rings in aqueous solutions of polyethylene oxide (PEO400) and hydrolysed polyacrylamide (PAMH25). We study the canonical vortex ring as a caricature problem to the phenomenon of turbulent polymer drag reduction. PAMH25 has a similar infinite shear viscosity, ten times the zero shear viscosity and a thousand times the relaxation time of PEO400. We study the vortex rings generated by the trapezoidal motion of a piston-cylinder mechanism using PIV and PLIF at constant impulse. We see that PAMH25 drastically affects the propagation properties and the structure of the vortex ring, while PEO400 shows a behaviour similar to water. We conclude that PAMH25 retards the roll-up process of the ring, due to both the large range of plateau viscosities and large relaxation time. We surmise that the behaviour of the vortex ring observed might be used to unravel the mechanism of polymer drag reduction.

中文翻译：

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聚合物溶液对自由平移涡环传播和结构的影响

摘要 我们通过实验研究了涡环在聚环氧乙烷 (PEO400) 和水解聚丙烯酰胺 (PAMH25) 的水溶液中的传播。我们研究规范涡环作为湍流聚合物减阻现象的漫画问题。PAMH25 具有类似的无限剪切粘度，是 PEO400 的零剪切粘度的十倍和松弛时间的千倍。我们使用 PIV 和 PLIF 在恒定脉冲下研究由活塞-气缸机构的梯形运动产生的涡环。我们看到 PAMH25 极大地影响了涡环的传播特性和结构，而 PEO400 表现出类似于水的行为。我们得出结论，PAMH25 延缓了环的卷起过程，这是由于大范围的平台粘度和大的弛豫时间。