Coupled dynamics of a thin lubricating film with hydrodynamic instabilities in a conjugated liquid layer

共轭液体层中具有流体动力学不稳定性的薄润滑膜的耦合动力学

基本信息

批准号：
209627097
负责人：
Professor Dr. Steffen Hardt
金额：
--
依托单位：
Center of Smart Interfaces (CSI) - Understanding and Designing Fluid Boundaries
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2012
资助国家：
德国
起止时间：
2011-12-31 至 2018-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/209627097?language=en
关键词：
Coupled dynamics thin lubricating film

项目摘要

In the course of the originally funded project DI 1689/1-1, the Bénard-Marangoni (BM) cellular convective instability, driven by a temperature gradient, was generated in a liquid layer. The convection cells cause interfacial deformations of a thin immiscible film placed between the layer and the supporting substrate. The deformations can be fixated if the film fluid is a polymer curable by irradiation with ultraviolet (UV) light. Re-establishing BM convection in a liquid layer placed on such a pre-structured substrate leads to a flow pattern which is exactly identical to the one used to structure the substrate, i.e. the hydrodynamic pattern formed in the fluid volume is 'stored' at its boundary and retrieved from it again. This follow-up proposal aims at elaborating on this principle in more detail. The stability regime of the conjugated liquid layer system will be probed by a weakly non-linear analysis as well as by full numerical simulations. Subsequently, the description of such coupled self-organizing subsystems will be cast in a more generic mathematical framework to identify a class of coupling operators which cause an emergent behavior of the full system. This means that its dynamics (i.e. of the conjugated layers) may be qualitatively different from that of its constituents (i.e. the individual liquid layers). Solidification of the film is not required; the pattern-conserving effect the thin film has on the upper layer remains functional as long as the characteristic time the liquid-liquid interface takes to flatten after a temporary removal of the driving temperature gradient is much larger than the decay time of the convection in the thicker layer. This property will be used to experimentally explore convection-diffusion dynamics of a dissolved/suspended species subjected to BM convection. Storing and retrieving a hydrodynamic pattern from the boundary of a fluid domain may be feasible for a broader class of flow phenomena. To this end, the Faraday instability emerging in a liquid layer upon exposure to vertical vibrations will be experimentally examined when a thin liquid film is placed between the liquid layer and the solid substrate. By contrast to BM convection, the Faraday instability implies linear oscillatory flow, whose shear stress does not necessarily cause a time-averaged deformation of the liquid film. Nevertheless, the presence of the film may render the conjugated system non-linear, so that a time-averaged deformation may be observed. Via solidification by UV light such deformations may be stored at the fluid boundary and analyzed by a profilometer, while its hydrodynamic 'information content' may be retrieved in a subsequent experiment. With this work we intend to establish the fundaments of a new engineering tool allowing not only to tune the stability regimes of certain flows, but also to 'engrave' certain flow characteristics into the domain boundary. We call this novel principle hydrodynamic pattern memory.

在最初资助的项目DI 1689/1-1的过程中，由温度梯度驱动的Bénard-Marangoni（BM）细胞对流不稳定性在液体层中产生。构造单元会导致薄膜和支撑基底物之间的薄膜的界面变形。如果薄膜流体是通过紫外线（UV）光照射可治愈的聚合物，则可以固定变形。将BM寄存在放置在这种预结构底物上的液态层中的BM运输导致流动模式，该流量与用于构造底物的底物完全相同，即在流体体积中形成的流体动力图案在其边界处“存储”并从中再次检索。这项后续提案旨在更详细地详细阐述这一原则。共轭液体层系统的稳定性将通过弱非线性分析以及完整的数值模拟来探测。随后，对此类耦合自组织子系统的描述将以更通用的数学框架进行投放，以识别一类耦合操作员，从而导致完整系统的新兴行为。这意味着其动力学（即共轭层）可能与其成分（即单个液体层）的动力学不同。不需要胶片的固化；只要液体液体界面暂时去除驱动温度梯度后，薄膜对薄膜对上层的效果就可以保持起作用。该特性将用于实验探索受BM生成的溶解/悬浮物种的转化扩散动力学。从流体结构域的边界中存储和检索流体动力模式可能是可行的，对于更广泛的流动现象。为此，当将薄液膜放在液态层和固体底物之间时，将在暴露于垂直振动时在液态层中出现的法拉第不稳定。与BM结构相比，法拉第不稳定意味着线性振荡流，其剪切应力不一定会导致液体膜的时间平均变形。然而，膜的存在可能会导致共轭系统非线性，以便可以观察到时间平均变形。通过紫外线固化，这种变形可以存储在流体边界上并通过探测仪进行分析，而其流体动力“信息含量”可以在随后的实验中检索。通过这项工作，我们打算建立一种新的工程工具的基础，不仅可以调整某些流动的稳定性制度，还可以将某些流动特性“雕刻”到域边界中。我们称这种新颖的原理流体动力模式记忆。