Enstrophy transfer and local topology at the interfaces of large-scale structures in spatially developing compressible mixing layers

The isosurfaces of zero fluctuating streamwise velocity within the turbulent region of spatially developing compressible mixing layers are defined as the interfaces of high- and low-speed large-scale structures (LSSs). This study advances the knowledge of local flow characteristics at the interfaces of LSSs for different streamwise regions and compressibility (${M}_{c}=0.3$ and ${M}_{c}=0.8$). For the first time, enstrophy transfer is systematically analyzed at LSS interfaces, and local topology conditioned on interface orientation is used to explain flow patterns near these interfaces.