中文摘要：

近年来黏弹性流体流动的纯弹性不稳定现象引起了越来越多学者的关注与研究,与牛顿流体惯性不稳定现象不同,这种现象是由黏弹性流体流动中的弹性应力和黏性力之间相互作用,使得在较低的雷诺数Re下即可产生复杂的流动分岔不稳定现象.当流动中的弹性数较大时,在Re〈〈Rec（惯性不稳定性产生的临界雷诺数）下,黏弹性流体流动中也可能产生完全由弹性应力引起的纯弹性不稳定现象.以Taylor–Couette流动为基础,对黏弹性流体流动中产生纯弹性不稳定现象的研究现状从实验、理论分析和数值模拟3个方面进行总结.通过对比这3个方面,总结了弹性流动不稳定现象发生的过程与机理、流动不稳定性产生的影响因素及其作用方式,并对目前研究的不足之处以及今后可能的发展趋势作了分析和展望.

英文摘要：

Recently, more and more attention and research efforts have been paid to the elastic instabilities. Different from the Newtonian fluid instabilities induced by inertial stress, elastic instabilities are generated by the interaction between elastic stress and inertial stress that induces flow bifurcations even at extremely low Reynolds number （Re）. When the elasticity number （defined as the ratio between Deborah number De, defined as the ratio between the relaxation time of viscoelastic fluid and the characterized time scale of the flow, and Re） is relatively large, purely elastic instabilities could also happen in a viscoelastic fluid flow at Re Rec, where Rec is the critical Reynolds number ofinertial instabilities. Generally, the viscoelastic fluids are characterized by complicated rheological properties such as memory properties, shear-thinning, non-zero normal stress differences and stretch-induced deformation and so on, which makes it extremely diffcult to investigate the instabilities in viscoelastic fluid flows. Nonetheless, based on various experiment studies, theoretical analyses and numerical simulations, some understandings on this phenomenon have been achieved. The research of elastic instabilities is of great importance in plastic processing and molding, rheology of polymer solutions and other fields. In the present paper we make a review on the state-or-the-art of the research on purely elastic instabilities mainly from the experimental, theoretical and numerical simulation results based on Taylor-Couette flow. Through comparisons among the three aspects, summaries and concluding remarks of the mechanism, evolvement and key factors of purely elastic instability are drawn. Furthermore, analyses of some existing problems and prospects for future studies in this field are given.