Multiphase Large Eddy Simulations

单相计算流体力学的主要支柱之一是在大涡模拟(LES)的背景下进行过滤，以相对较低的计算成本提供准确的结果。将这一想法推广到多相流，除了过滤的湍流外，还需要处理过滤的界面。虽然在过去的十年里，湍流中的过滤界面已经得到了数学描述，但对于这个问题，方法和闭合模型还没有很好的建立。对于这类大涡模拟多相流的一般描述方法可以引领多相计算流体力学的一个新方向，就像上世纪70年代单相流大涡模拟的引入那样。新的方法将可用于研究复杂的多相问题，这些方法将介于已建立的完全解决和未解决的方法之间。亚利桑那州坦佩的赫尔曼教授开发了一种非常有前途的方法，用于处理过滤界面，重点放在喷雾的初级破裂上。这一方法将在博士毕业后期间推广到泡状流。这包括对本方法的改进，实现新的闭合模型，以及用直接数值模拟和实验数据进行详细的验证和验证。最后，对超出已有方法可能性的复杂多相问题的模拟将显示出新方法的巨大潜力。对于申请者个人来说，逗留将使他能够在自己的初级研究小组中进行过滤接口领域的积极研究。为此，博士后期间学习的技能和建立的科学网络将是基础。这种对大涡模拟类多相流模拟的研究兴趣在德国是独一无二的，它将在处理完全分辨和非分辨界面的现有研究小组之间架起桥梁。

One of the main pillars in single-phase computational fluid dynamics is filtering in the context of Large Eddy Simulations (LES) providing accurate results with relatively low computational costs. By extending this idea to multiphase flows, a filtered interface needs to be handled in addition to the filtered turbulence. Although filtered interfaces in turbulent flows have been mathematically described in the last decade, methods as well as closure models are not well established for this problem. A general method for such LES-like multiphase flow descriptions can lead into a new direction in multiphase computational fluid dynamics like the introduction of single-phase flow LES did in the 70s of the last century. New methods will be available for investigating complex multiphase problems, which would be positioned between the established fully resolved and unresolved methods.A very promising method for handling filtered interfaces with focus on the primary break-up of sprays was developed by Prof. Herrmann in Tempe, Arizona. This method will be extended to bubbly flows during the post-doc period. This includes the advancement of the present method, implementing new closure models, and detailed verification and validation with data from direct numerical simulations as well as from experiments. Finally, the simulation of complex multiphase problems that are exceeding the possibilities of the established methods will show the high potential of the new approach. For the applicant personally, the stay will enable him to do active research in the area of filtered interfaces in his own junior research group. For this purpose, the learned skills and the built scientific network during the post-doc period will be the fundament. This research interest in LES-like multiphase flow simulations is unique in Germany and it will bridge the established research groups dealing with fully resolved and non-resolved interfaces.