MAE Seminar: Integrated Turbulence Simulations and Multiphase Research

Abstract: Significant progress has been made in the past decade to predict atomization using detailed numerical simulations. Much of the early work in this area focused on atomization in simple geometries, for example liquid jets issuing from straight pipes into rectangular channels with and without crossflows, e.g., the atomization of liquid jets in crossflow, and the injection of liquids jets into stagnant environments typical for Diesel injectors. However, in the past couple of years, simulations of realistic complex  injectors have become viable, offering a path to study application-relevant geometries not only via experiments, but also via detailed simulations. In this seminar, numerical techniques will be discussed to enable the predictive simulation of atomization in complex geometries. These include conservative techniques to capture the motion of the phase interface, unstructured meshing approaches to handle complex geometries, and approaches to tackle the vast range of scales present in atomization processes, ranging from centimeter scales of the injector down to the sub-micron scale of the smallest drops. In addition to validation results for simpler injector geometries, simulation results for a realistic high-shear gas turbine injector consisting of multiple liquid jets injecting into a swirling crossflow will be presented and compared to available experimental data for the configuration. The results highlight the current capabilities to predict atomization in realistic configurations using detailed simulations, but also show the need for continued improvement of the numerical techniques to simulate atomization. Finally, a dual-scale modeling approach will be discussed to tackle atomization simulations in a Large Eddy Simulation (LES) framework. Here, the dual nature of surface tension on small scales may necessitate novel modeling approaches that go beyond the classical cascade hypothesis underlying most LES modeling approaches.

Bio: Marcus Herrmann received his diploma and Ph.D. in mechanical engineering from the University of Technology (RWTH) Aachen, Germany. He was a visiting scientist at the University of Technology Eindhoven, The Netherlands, and a postdoctoral fellow and research associate at the Center for Turbulence Research (CTR) at Stanford University. He joined the faculty of Arizona State University in 2007. His main research areas are numerical methods for simulating atomization in both low Mach number and fully compressible flows, and LES models for  turbulent interface dynamics. He currently serves as the editor-in-chief for the Americas of Atomization and Sprays.