Vortex and gas-liquid interface dynamics in multiphase flows

Overview

Mastering transport and mixing phenomena is key to the optimization of many industrial processes, including single- and multiphase chemical transformations, aeronautics and turbomachinery. However, analyzing the time-dependent flow fields based on primary variables such as velocity is usually not sufficient to capture the underlying mechanisms.

 

Lagrangian coherent structures (LCS) and their quantitative interpretation via finite-time Lyapunov exponents (FTLE) offer an alternative route with some unique advantages for revealing the coherent structures of a given flow field, which exhibits an ordered behavior characterized by the repelling and attracting material surfaces. In principle, these surfaces behave like dynamic boundaries that organize the main flow behavior, providing an intuitive way to explore and understand the governing phenomena, even for very complex problems such as vortex motion, interfacial transport and micro-mixing.

At ITS, we have developed our own post-processing tool, postAtom, to explore the large-scale data generated by turboSPH simulations, velocity field measurements and grid-based Eulerian solvers. A unique feature of postAtom is the highly efficient GPU implementation of FTLE field computations, which enables real-time interactive analysis of FTLE fields in 3-D datasets. Such analysis allows us to identify mixing patterns on different length scales together with their temporal evolution, leading to a unique insight into the local phenomena and the possibility to track the influence of geometric variations.

Sources and relevant publications


Journal Articles
Progress in the Smoothed Particle Hydrodynamics Method to Simulate and Post-process Numerical Simulations of Annular Airblast Atomizers
Chaussonnet, G.; Dauch, T.; Keller, M.; Okraschevski, M.; Ates, C.; Schwitzke, C.; Koch, R.; Bauer, H.-J.
2020. Flow, turbulence and combustion, 105, 1119–1147. doi:10.1007/s10494-020-00174-6
Analyzing the Interaction of Vortex and Gas–Liquid Interface Dynamics in Fuel Spray Nozzles by Means of Lagrangian-Coherent Structures (2D)
Dauch, T. F.; Ates, C.; Rapp, T.; Keller, M. C.; Chaussonnet, G.; Kaden, J.; Okraschevski, M.; Koch, R.; Dachsbacher, C.; Bauer, H.-J.
2019. Energies, 12 (13), Article: 2552. doi:10.3390/en12132552
Highly efficient computation of Finite-Time Lyapunov Exponents (FTLE) on GPUs based on three-dimensional SPH datasets
Dauch, T. F.; Rapp, T.; Chaussonnet, G.; Braun, S.; Keller, M. C.; Kaden, J.; Koch, R.; Dachsbacher, C.; Bauer, H.-J.
2018. Computers & fluids, 175, 129–141. doi:10.1016/j.compfluid.2018.07.015
Conference Papers
Analyzing Primary Breakup in Fuel Spray Nozzles by Means of Lagrangian-Coherent Structures
Dauch, T. F.; Ates, C.; Rapp, T.; Keller, M. C.; Chaussonnet, G.; Kaden, J.; Okraschevski, M.; Koch, R.; Dachsbacher, C.; Bauer, H.-J.
2019. Proceedings of the 14th SPHERIC International Workshop, Exeter, UK, June 25-27, 2019, 120–127