This colloquium addresses recent advances in understanding the physics of shock-wave/turbulence interaction, a phenomenon ubiquitous in high-Reynolds and high-Mach number flows. The colloquium focuses on conditions relevant to hypersonic applications, where strong compressions tighten the coupling between the thermodynamic state of the gas and hydrodynamics, potentially leading to thermo-chemical non-equilibrium driven by turbulence mixing and shock-induced compression.

To provide a comprehensive discussion, the colloquium will be structured around two complementary topics: (1) the interaction of shock waves with homogeneous isotropic turbulence (HIT), and (2) the interaction of shock waves with wall-bounded turbulent boundary layers.

The interaction of HIT will be utilized to explore fundamental aspects of the problem using numerical simulations and theoretical approaches. Topics include, among others, turbulence–thermo-chemistry coupling downstream of the shock, mechanisms responsible for the amplification of turbulence modes across it, and the role of compressibility and non-equilibrium effects. Improving understanding of these processes is essential for developing predictive turbulence models in Reynolds-averaged and large-eddy simulation frameworks.

In wall-bounded configurations, recent advances in quantifying the effects of wall cooling and surface roughness will be discussed, with particular emphasis on their implications for wall modeling. Contributions may also address extensions of current knowledge on three-dimensional shock-wave/boundary-layer interactions, where no statistically coherent spatial directions can be identified. In this context, emphasis is also placed on the role of fluid–structure interaction and conjugate heat transfer effects.

Two key scientific questions arise in this context:

"How does increasing stagnation energy modify the coupling between turbulence, shocks, and thermochemical nonequilibrium processes in high-speed flows?"

In homogeneous isotropic turbulence, increasing stagnation energy promotes the onset of chemical dissociation and vibrational excitation. These phenomena may be triggered both by turbulence fluctuations and shock-induced compression, with characteristic timescales that can become comparable to those of the turbulence, leading to strongly non-equilibrium flows. Because of the highly nonlinear coupling between turbulence, thermochemistry, and shock dynamics, modeling remains a major challenge for turbulence models.

In wall-bounded configurations, additional mechanisms influence the interaction, including wall cooling and surface chemistry. In particular, the intense heat fluxes associated with shock-wave/boundary-layer interactions can give rise to significant conjugate heat transfer effects, which may alter the structure and dynamics of the interaction. Understanding the fundamental implications of these processes and their representation in reduced-order models is therefore a central question for the colloquium.

"What are the governing drivers of hypersonic shock–turbulence interactions across the parameter space?"

Hypersonic shock–turbulence interactions span a wide parameter space defined by turbulence intensity, Mach number, wall cooling, and thermochemical conditions. Exploring this space enables the identification of distinct interaction regimes and the dominant mechanisms governing each of them.

In homogeneous turbulence, parameter variations influence the relative importance of vortical, dilatational, and entropic fluctuations, as well as their coupling with shock dynamics and chemical non-equilibrium processes. In wall-bounded configurations, wall temperature, surface characteristics, and inflow turbulence determine separation behaviour, heat transfer, and pressure fluctuations, which are also coupled with non-equilibrium phenomena. Hence, establishing the governing influences across these parameters is crucial for enabling meaningful comparisons between different flow configurations, as well as between experimental and numerical studies, where boundary conditions and external constraints may differ, and therefore represent a key topic for discussion in the colloquium.

We invite you to submit theoretical, numerical, or experimental contributions concerning these topics.

Chairperson: Mario Di Renzo, Università del Salento, Italy

Co-Chairperson 1: Prof. Christoph Wenzel, University of Stuttgart, Germany

Co-Chairperson 2: César Huete Ruiz de Lira, Universidad Carlos III de Madrid, Spain