An all-topology two-fluid model for two-phase flows derived through Hamilton's Stationary Action Principle
Abstract
We present a novel multi-fluid model for compressible two-phase flows. The model is derived through a newly developed Stationary Action Principle framework. It is fully closed and introduces a new interfacial quantity, the interfacial work. The closures for the interfacial quantities are provided by the variational principle. They are physically sound and well-defined for all types of flow topologies. The model is shown to be hyperbolic, symmetrizable, and admits an entropy conservation law. Its non-conservative products yield uniquely defined jump conditions which are provided. As such, it allows for the proper treatment of weak solutions. In the multi-dimensional setting, the model presents lift forces which are discussed. The model constitutes a sound basis for future numerical simulations.
Keywords
Cite
@article{arxiv.2509.26298,
title = {An all-topology two-fluid model for two-phase flows derived through Hamilton's Stationary Action Principle},
author = {Ward Haegeman and Giuseppe Orlando and Samuel Kokh and Marc Massot},
journal= {arXiv preprint arXiv:2509.26298},
year = {2026}
}