Modeling and Stability Analysis of Prototype Mixed Kinematic Bulk, Free Surface, and Interfacial Flows of Viscoelastic Fluids

这项拨款是为了解决与聚合物和聚合物基复合材料相关的问题，这些材料被认为是美国安全的关键。大多数聚合物和复合材料制造工艺的基本部分涉及聚合物在有或没有增强的任意形状的空腔中的流动。流程的吞吐量和产品质量往往受到流动不稳定性的影响。纯弹性不稳定性的存在表明，所有聚合物加工操作，无论它们可能多么缓慢，都容易出现不稳定性。因此，了解流体弹性对具有代表性的体流、自由面和界面流动的流动和稳定性的影响是至关重要的。采用完全并行化的高阶有限元技术，研究粘弹性流体的二维和三维自由表面和界面流动。具体地说，这项工作将集中于研究剪切/拉伸混合流动中由于流体弹性而引起的流动修正，以及研究流体弹性和非平衡能量效应对这类流动稳定性的作用。特别值得关注的是确定在聚合物和复合材料加工中经常遇到的混合运动流动中导致粘弹性不稳定性的机制(S)。

This is a grant to address problems related to polymeric and polymer matrix composite materials that have been identified as being key to the security of the U.S. The basic part of most polymer and composite materials manufacturing processes involves flow of polymers in cavities of arbitrary shape with or without reinforcement. Process throughput and product quality are often limited by the onset of flow instabilities. The existence of purely elastic instabilities suggest that all polymer processing operations, however slow they may be, are prone to instabilities. For this reason understanding the influence of fluid elasticity on flow and stability of representative bulk, free surface and interfacial flows is crucial. Fully parallelized, higher-order finite element techniques will be used to study a number of prototype two and three-dimensional free surface and interfacial flows of viscoelastic fluids. Specifically, the work will focus on investigating flow modifications due to fluid elasticity in mixed shearing/elongational flows as well as examining the role of fluid elasticity and non-equilibrium energetic effects on stability of this class of flows. Of particular interest is to identify the mechanism(s) that are responsible for viscoelastic instabilities in mixed kinematic flows which are routinely encountered in processing of polymers and composite materials.