Experimental, numerical and analytical investigation of droplet oscillation of a viscoelastic fluid

粘弹性流体液滴振荡的实验、数值和分析研究

• 批准号: 330615302
• 负责人: Professor Dr.-Ing. Martin Oberlack
• 金额: --
• 依托单位: Institut für Strömungslehre und Wärmeübertragung
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/330615302?language=en
• 关键词: Experimental; numerical; analytical; investigation; droplet; Experimental; numerical; analytical; investigation; droplet

Oscillating droplets occurring in innumerous production and energy conversion processes are a subject of scientific interest. The deviation from a sphere increases the surface, which enhances the rate of transfer for mass, momentum and energy. Liquids involved in production processes of bio- and chemical engineering, particularly, polymer powders by spray drying and in the aeration of liquids with dissolved proteins and bacteria, may exhibit viscoelastic behaviors. In the present project we intend to jointly develop a deeper understanding of the motions within viscoelastic droplets and, as a long-term goal, to explain their influences on transport processes across the interface. For this we will employ sophisticated experimental, numerical and analytical methods. Most important, the droplet deformations involved are allowed to include nonlinear fluid behavior.For this, new numerical methods based on Discontinuous Galerkin method (DG) will be developed, which allow an hp-accurate simulation. Different from classical approaches, the key goal is a sub-cell accurate sharp-interface hp-accurate simulation. A broad variety of specific tools have already been developed for this. The numerical difficulties for simulating viscoelastic models are less severe in the context of DG compared to classical numerical methods, e.g. FVM. Additionally, tensor-polynomial basis ideas, very successfully employed for algebraic stress models in the context of turbulence, will also be adopted. Therein it led to fast and robust schemes, which, due to the close similarity of equations, will also be employed for the present viscoelastic models.Additionally, a weakly nonlinear analytical approach will be developed such that it can represent the time dependency of the oscillation frequency. Nonlinearity is essential, as the oscillation frequency decreases with increasing oscillation amplitude, and, further, the times spent in the oblate and prolate states of deformation are no longer equal. The coupling of the oscillation modes in nonlinear motion is an important aspect in the decay of oscillations. These results will be a crucial benchmark for the DG-based numerical scheme.Both analytical and numerical approaches will be compared to experimental results. In order to do so, experiments will deliver both material parameters as well as dynamical results such as oscillation frequencies, droplet shapes, etc. In the linear limit, the dampened drop shape oscillations themselves will be used for determining the polymeric deformation retardation time scale of the test liquid needed for the computations.The present proposal is part of a two-phase project where in the second phase it is intended to study mass and energy transfer across the droplet-surface. Physically this corresponds to a non-material interface, resulting in different difficulties both numerically as well as experimentally. These effects constitute key design parameters for many applications.

在无数生产和能量转化过程中发生的振荡液滴是科学意义的主题。偏离球体的偏差会增加表面，从而提高了质量，动量和能量的传递速率。涉及生物和化学工程生产过程的液体，特别是通过喷雾干燥以及在溶解蛋白和细菌的液体的曝气中，可以表现出粘弹性行为。 在本项目中，我们打算共同对粘弹性液滴中的动作进行更深入的了解，并作为一个长期目标，以解释它们对整个界面运输过程的影响。为此，我们将采用复杂的实验，数值和分析方法。最重要的是，允许涉及的液滴变形包括非线性流体行为。为此，将开发基于不连续的Galerkin方法（DG）的新数值方法，从而允许HP准确的模拟。与经典方法不同，关键目标是一个子电池精确的尖锐界面HP精确模拟。为此已经开发了各种特定的工具。与经典的数值方法相比，在DG的背景下，模拟粘弹性模型的数值困难不那么严重。 FVM。此外，在动荡的背景下，在代数应力模型中非常成功地使用了张量 - 多项式基础思想。这导致了快速，强大的方案，由于方程的紧密相似性，也将用于当前的粘弹性模型。从附属上讲，将开发出一种弱的非线性分析方法，以代表振荡频率的时间依赖性。非线性是必不可少的，因为振荡频率随着振荡幅度的增加而降低，此外，在扁平和扁平的变形状态下，所花费的时间不再相等。非线性运动中振荡模式的耦合是振荡衰减的重要方面。这些结果将是基于DG的数值方案的至关重要的基准。分析方法和数值方法将与实验结果进行比较。为此，实验将提供材料参数和动力学结果，例如振荡频率，液滴形状等。在线性极限中，在线性极限中，降低的滴度振荡本身将用于确定聚合物变形迟缓时间范围的计算所需的测试量的一部分。液滴表面。从物理上讲，这对应于非物质界面，在数值和实验上都带来了不同的困难。这些效果构成了许多应用程序的关键设计参数。