The turbulent/non-turbulent interface (TNTI) is an irregular boundary between turbulent and irrotational flow, which widely exists in various flow types, such as turbulent boundary layer, combustion flame front, turbulent patches in atmosphere and ocean, pollutant dispersion, etc. Due to its importance in affecting the intermittent characteristic and the mixing and entertainment process of turbulent flows, TNTI has become one of the most active branches of turbulent research in the past decades. Nevertheless, the scientific community still faces various challenges that hinder an ultimate characterization and modelling of TNTI. The unresolved problems, to name a few, spread from the lack of a well-accepted definition of TNTI to the intriguing origin of its fractal multi-scale nature. The dynamics of TNTI, which is the key for the mechanism of the exchange of mass, momentum and energy between turbulence and irrotational outflows, also deserves an interpretation from the perspective ofturbulent structures. 

This book presents the proceedings of the "IUTAM Symposium on turbulent/non-turbulent interface in turbulent shear flow' will be held in 2024, Oct.  This book will collect the up-to-date works from active researchers worldwide to anchor the state-of-art knowledge of TNTI and to envision the future direction of this field. The focus includes but is not limited to the scaling for the geometries, kinematics and dynamics of TNTI, the role of turbulent structures in the entrainment process, multiphase flow with TNTI, high-fidelity turbulent model that accounts for the intermittency of TNTI, and reduce-order-model-based prediction for engineering application. The content is a valuable reference for researchers, engineers and students who are interested in understanding the complex behavior of TNTI in turbulent shear flows. This is an open access book.