Half a century of Multiphase Flow

In 2023, the International Journal of Multiphase Flow (IJMF) marked fifty years since the publication of its first issue. This editorial looks back at the circumstances that led to the creation of the Journal and at the role it has played in bringing together a scientific community that, at the time, was still scattered across several disciplines and engineering traditions. The anniversary was celebrated in Vienna with a meeting that gathered researchers from across the broad spectrum of multiphase-flow science and provided an occasion to reflect on both the history of the Journal and the evolution of the field itself. One outcome of that meeting was a series of five collective perspective papers devoted to bubbles and bubbly flows, drop-laden flows, particle-laden flows, experimental methods for dispersed multiphase flows, and numerical methods for multiphase flows. Looking back over the Journal’s first half-century, and forward to the questions and methods now reshaping the field, we reflect on the continuing place of IJMF within a broad and evolving multiphase-flow community.