Absolute instability in viscoelastic mixing layers
Absolute instability in viscoelastic mixing layers
复制标题
粘弹性混合层的绝对不稳定性
DOI：
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发表时间：
2013
期刊：
影响因子：
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通讯作者：
T. Zaki
中科院分区：
文献类型：
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作者：
Prasun K. Ray;T. Zaki
研究了粘弹性平面混合层的时空线性稳定性。一个单参数的家庭的速度分布被用作与参数，S，控制量的剪切和回流的基状态。聚合物稀溶液中的粘弹性的影响与Oldrophil-B和FENE-P本构方程建模。两种模型都需要指定聚合物弛豫和对流时间尺度的比率（Weissenberg数，We）以及溶剂和溶液粘度的比率（β）。对于FENE-P型号，还必须指定最大聚合物延展性L。我们研究这些参数的变化沿着与雷诺数，Re，影响的最小值S的流动变得局部绝对不稳定。使用Oldroplast-B模型，粘弹性的影响几乎完全被弹性E* ε（1-β）WeRe捕获，并且随着弹性的增加，Scrit减小，即，弹性是不稳定的一个简单的AP…
The spatiotemporal linear stability of viscoelastic planar mixing layers is investigated. A one-parameter family of velocity profiles is used as the base state with the parameter, S, controlling the amount of shear and backflow. The influence of viscoelasticity in dilute polymer solutions is modeled with the Oldroyd-B and FENE-P constitutive equations. Both models require the specification of the ratio of the polymer-relaxation and convective time scales (the Weissenberg number, We) and the ratio of solvent and solution viscosities (β). The maximum polymer extensibility, L, must also be specified for the FENE-P model. We examine how the variation of these parameters along with the Reynolds number, Re, affects the minimum value of S at which the flow becomes locally absolutely unstable. With the Oldroyd-B model, the influence of viscoelasticity is shown to be almost fully captured by the elasticity, E*≡(1−β)WeRe, and Scrit decreases as elasticity is increased, i.e., elasticity is destabilizing. A simple ap...