Reactive Multiphase Flows: Interfacial Chemistry in Dynamic Transport Systems

Reactive multiphase flows underpin a wide range of energy, environmental, and chemical technologies, yet their predictive description remains limited. Although interfaces are now widely recognised as chemically active, most theoretical and computational frameworks continue to treat them as quasi-steady boundaries or incorporate their effects through empirical closures. This Perspective argues that such approaches are fundamentally inadequate when reaction, transport, and hydrodynamic timescales become comparable and when reaction-driven interfacial forces actively restructure phase distributions. We critically examine the limitations of prevailing modelling paradigms using dimensionless reasoning and order-of-magnitude estimates, highlighting how coupled Damköhler, Marangoni, and capillary effects undermine model transferability across operating regimes. By synthesising advances in operando diagnostics, interface-resolved simulations, and physics-informed data-driven methods, we propose a unifying framework that treats interfaces as dynamically evolving, rate-determining subsystems. We further articulate a set of concrete, testable research challenges that define a forward-looking agenda for predictive design. This perspective aims to shift reactive multiphase flow research from descriptive integration toward quantitatively grounded, mechanism-based understanding across diverse application domains.