Weakly compressible smoothed particle hydrodynamics is used to investigate aircraft fuel jettison using a single-phase model. Fuel simulations are coupled to the aircraft computational fluid dynamics flowfield using cell containment checks on the finite-volume mesh to locate any smoothed particle hydrodynamics (SPH) particle within the mesh, after which the local flow velocity vector is retrieved and then used to apply an approximate aerodynamic force to the SPH particle based on a continuum correction to discrete droplet calculations. Further downstream, the SPH simulation may be continued, or a switch may be made to implicit particle tracking (IPT) in order to accelerate the simulation. Comparison to IPT results shows that a fluid model of the initial continuum breakup of the jet is required, but following this transition to IPT is reasonable to reduce computation time. Models are validated against volume of fluid (VOF) simulations, with the runtime of the proposed model being approximately 100 times less than the VOF, and good qualitative agreement is also found compared to recorded flight results.

Volcanic ash is an aerial hazard to both aircraft and local populations, hence efforts to monitor and quantify its presence are underway in many regions, both to protect airspace users and as a modeling tool for volcanology. One direct approach is to acquire in-situ ash samples using an unmanned vehicle, but this introduces possible bias in the samples due to the collector system, especially across the full range of ash particle sizes. This work explores an open impact type design of miniaturized airborne ash collector and quantifies the influence of the collector geometry on the measured particle size distribution. Results indicate that the distribution of sizes measured can be strongly influenced by the collector design, owing to the influence of the geometry on the aerodynamics and hence the particle trajectories. Comparisons to experimental flight data illustrate that the simulations provide a representative model, and that a design featuring a bluff fore-body separates and mixes the flow, making it more capable of capturing small particles than a planar surface in isolation.

Volcanic ash is an aerial hazard, and efforts to monitor and quantify its presence remain underway in many regions both to protect aircraft and as a tool for volcanology. One approach is to acquire ash samples using an unmanned vehicle, but this introduces possible bias in the samples due to the collector system, especially across the full range of ash particle sizes. This work explores a particular design of miniature airborne ash collector and quantifies the influence of the collector geometry on the collected particle size distribution. Results indicate that the distribution of sizes collected can be strongly influenced by the collector design, owing to the influence of the geometry on the aerodynamics and hence the particle trajectories. A design featuring a bluff body that separates and mixes the flow is more capable of capturing small particles than a planar surface in isolation.

Simulation of an aircraft jettisoning fuel using a single phase liquid model is investigated. Weakly compressible smoothed particle hydrodynamics (WCSPH) is used to model the fuel, and an approximate aerodynamic force implemented based on a continuum correction to discrete droplet calculations. The use of ghost air particles is also investigated to provide pressure information transfer. The proposed WCSPH model is compared to volume of fluid (VOF) simulations for a droplet and a jet in perpendicular flow, and breakup is found to be qualitatively similar. Tests are also done using the high lift common research model (HL-CRM) and Japan standard model (JSM) geometries, which provide physically realistic results.