The Cross-scale Transfer of Kinetic Energy in Gaseous Detonations

Multi-scale interactions and transfer of kinetic energy in gaseous detonations over a characteristic detonation cell cycle are fundamental to understanding and modeling turbulent gaseous detonations. In order to investigate these phenomena, highly resolved three-dimensional simulations of gaseous detonations in hydrogen/air mixtures at atmospheric pressure are analyzed in this study. Fully compressible Navier-Stokes equations with complete molecular transport and the state-of-the-art chemical kinetics model are solved in a rectangular channel using Athena-RFX. Spatial filtering is performed to characterize various terms directly in the kinetic energy transport equations across various length scales using a high-order, spatially local, and spectrally sharp differential filter. In particular, we aim to address the following open questions: a) How does energy production occur on the smallest scales in a detonation? b) Can such small-scale energy get transported to larger scales to organize into dynamically important coherent structures such as forward jets during a cell cycle? c) What is the mechanism of such inter-scale energy transport? While addressing these questions, we also discuss the precise resolution requirements to capture the small-scale vorticity dynamics in the front, and thus the potential effects which lack of resolution can have on the overall accuracy of the detonation simulations.