Multiphase flows

What happens when something else gets carried by the flow — droplets, aerosols, plastics, sediment, ice — and the carrier is turbulent? That question runs through the group’s longest-standing thread of work. Inertia, buoyancy, settling, evaporation and condensation, and mixing all compete, and the most interesting physics tends to live exactly where things change fastest: at sharp interfaces.

Through the EU Horizon 2020 Marie Skłodowska-Curie network COMPLETE (Cloud-MicroPhysics-Turbulence-Telemetry), the lab tackled cloud-edge dynamics head-on. Cloud-environment DNS with Lagrangian particles let us watch entrainment, detrainment and droplet evolution at cloud edges in genuine resolution (Nair et al., 2020, 2021, 2023; Huang et al., J. Fluid Mech. 2023; Huang et al., Q. J. R. Met. Soc. 2025). The current NERC project on droplet dynamics in intermittent cloud-turbulence pushes further: resolved particle–turbulence interactions across cloud–environment interfaces, with the explicit aim of bridging laboratory-scale physics and the parameterised cloud microphysics that operational weather models actually use.

A second thread tracks particles across density interfaces — inertial, settling, buoyant — including plastics and microplastics, transient forces at sharp stratification, preferential clustering, and particle-laden gravity and turbidity currents. And on the atmospheric side, aerosol-cloud interactions through ship tracks (Ribeiro et al., Geophys. Res. Lett. 2024), particle dispersion, and marine and coastal transport problems link the multiphase physics to environmental flows the public can see from a satellite.

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