7TROPICAL Multi-Fluid Modeling of Energy and Momentum Exchange in Spray-Laden Hurricane Boundary Layer

Ocean spray generated by intense winds plays a crucial role in the exchange of heat, momentum, and turbulent kinetic energy between the ocean and atmosphere. These exchanges strongly influence key hurricane characteristics such as its intensity and path. Specifically, ocean spray varies the net energy supply driving the storm by altering air turbulence, heat transfer, and wind profiles. Accurately modeling these complex interactions is essential for capturing hurricane dynamics and structure.

The current work employs an Eulerian multifluid model to simulate a hurricane boundary layer laden with a polydisperse ocean spray. This approach treats dry air, water vapor, and spray droplets of various sizes as distinct phases, each governed by its own conservation equations for mass, momentum, and energy. These equations are interconnected through interfacial transfer terms that account for the exchange of mass, momentum, and energy between the phases. While computationally more expensive, the multifluid approach enables a more accurate representation of interphase interactions and coupling effects. This offers a more accurate description of turbulent airflows laden with a polydisperse evaporating spray than a conventional mixture approach that treats the air-droplet mixture as a single fluid with averaged properties.

We conducted a comprehensive numerical and analytical study based on both mixture and multifluid models and compared the predicted vertical distributions of sensible and latent heat fluxes, wind velocity, and turbulent transport intensity under different atmospheric conditions. Our findings reveal significant differences between the results produced by the two models. They speak strongly in favor of employing multifluid models to accurately capture the effects of spray on the boundary layer dynamics and structure of hurricanes.

The authors acknowledge support by grants from the National Science Foundation, U.S.A. under Award No. 2302221