Abstract: The effect of spatial resolution on local propagation velocity of the Turbulent/Non-Turbulent Interface (TNTI) is documented. A TNTI-local coordinate system and a Reynolds decomposition based on a TNTI-conditional averaging operation are introduced and used to assess the local velocity field and the mass and momentum balances at theTNTI layer. A clear jump of the TNTI-averaged Reynolds shear stress exists through the TNTI layer and the TNTI-averaged fluid velocity normal to the TNTI is determined by the correlation between the TNTI normal vector and the fluid velocity fluctuations around the TNTI-average fluid velocity. The TNTI-local fluid velocity field is compressive normal to the TNTI and stretching in the direction tangent to the TNTI, a structure that has important consequences.

Curriculum Vitae: Professor John Christos Vassilicos started his career at the University of Cambridge and was, since 2003, Professor of Fluid Mechanics at Imperial College London. His research is in the fundamentals and applications of turbulent flows. He published significant contributions in many aspects of turbulence theory supported by experimental and numerical data. To cite a few, he introduced the study of turbulent flows generated by fractal/multi-scale objects, discovered a new turbulence dissipation and interscale energy flux law for non-equilibrium turbulence as well as resulting turbulent wake and jet scaling laws, made contributions to the understanding of clustering of inertial particles in turbulent flows, and more recently to wall turbulence. He was awarded an ERC Advanced grant (2013-2018) and has been the PI of many European and UK Grants. He has supervised and trained 34 completed doctoral students and 14 post-doctoral researchers. Since 2019, Professor John Christos Vassilicos joined the Fluid Mechanics Laboratory of Lille (LMFL) and obtained a permanent senior researcher position (Director of Research) at the French National Centre for Scientific Research (CNRS).