Experimental and Computational Analysis of fluidic interfaces influenced by soluble surfactant

表面活性剂是许多工艺过程中必不可少的成分，如发泡或乳化。由于它们的两亲性，它们在流体界面上聚集并改变各自的界面性质。由于这些界面是运动的，并且不断变形和扩展，因此局部瞬时界面张力是最相关的参数。为了对可溶性表面活性剂的这一过程有更深入的定量理解，本提议有两个总体目标：通过实验分析，利用Golm方面最近开发的工具，将获得选定的同源系列表面活性剂在液/液界面上的基本吸附特性的完整知识，对连续生长的液滴和液滴的瞬态和谐波扰动进行研究。由于表面活性剂在界面处横向分布的直接测量是不可能的，因此迫切需要一种具有完全分辨率的考虑可溶性表面活性剂影响的界面动力学的两相Navier-Stokes流模拟的数值方法。在达姆施塔特方面最近的初步工作的基础上，提出了这种方法的发展。虽然实验测量将提供有意义的模拟所需的参数，但计算分析将特别澄清实验中的三维流体动力学。同时，将获得所需的定量理解，并用于改进和验证简化模型。

Surfactants are essential ingredients in many technological processes such as foaming or emulsification. Due to their amphiphilic character they assemble at fluidic interfaces and modify the respective interfacial properties. Since these interfaces are moving and are continuously deformed and expanded, the local instantaneous interfacial tension is a most relevant parameter. In order to obtain a deeper quantitative understanding of such processes with soluble surfactant, this proposal has two general objectives: By means of experimental analysis, employing tools recently developed at the Golm side, complete knowledge of basic adsorption properties for selected homologous series of surfactants at liquid/liquid interfaces will be obtained, performing studies with continuously growing drops and with transient and harmonic perturbations of drops. Since a direct measurement of surfactant distribution lateral at the interface is not possible, a numerical method for the simulation of two-phase Navier-Stokes flows with full resolution of the interface dynamics accounting for the influence of soluble surfactants is highly desired. The development of such a method is proposed here, building on recent preliminary work on the Darmstadt side. While the experimental measurements will provide the parameters required for meaningful simulations, the computational analysis will especially clarify the 3D hydrodynamics in the experiments. Together, the demanded quantitative understanding will be obtained and used to improve and validate simplified models.